Blum Integer Calculator

Enter a number to check if it's a Blum integer, or input a range to generate all Blum integers within that range.

Blum Integer Check or Generate

What is a Blum Integer?

A Blum integer is a natural number formed as the product of two distinct prime numbers \( p \) and \( q \). These two primes must satisfy the following conditions:

  • \( p \) and \( q \) are distinct prime numbers.
  • Both \( p \) and \( q \) are of the form \( 4t + 3 \), where \( t \) is an integer. In other words, \( p \mod 4 = 3 \) and \( q \mod 4 = 3 \).

If \( n = p \times q \), and \( p \) and \( q \) meet the above criteria, then \( n \) is a Blum integer.

How to Check if a Number is a Blum Integer

  1. Prime Factorization: Decompose the number into its prime factors.
  2. Modulo Operation: Check if both prime factors satisfy \( p \mod 4 = 3 \) and \( q \mod 4 = 3 \).
  3. If both conditions are satisfied, the number is a Blum integer. Otherwise, it is not.

Examples

Example 1: Is 15 a Blum Integer?

Solution:

1. Prime Factorization:

\( 15 = 3 \times 5 \).

2. Modulo Check:

\( 3 \mod 4 = 3 \)

\( 5 \mod 4 = 1 \)

Result: 15 is not a Blum integer because 5 does not satisfy \( p \mod 4 = 3 \).

Example 2: Is 1909 a Blum Integer?

Solution:

1. Prime Factorization:

\( 1909 = 23 \times 83 \).

2. Modulo Check:

\( 23 \mod 4 = 3 \)

\( 83 \mod 4 = 3 \)

Result: 1909 is a Blum integer because both prime factors satisfy the condition.

Example 3: Is 2023 a Blum Integer?

Solution:

Prime Factorization:

\( 2023 = 7 \times 17^2 \).

Reasoning:

2023 is not the product of two distinct primes.

Result: 2023 is not a Blum integer.

The First 100 Blum Integers

  • 21
  • 33
  • 57
  • 69
  • 77
  • 93
  • 129
  • 133
  • 141
  • 161
  • 177
  • 201
  • 209
  • 213
  • 217
  • 237
  • 249
  • 253
  • 301
  • 309
  • 321
  • 329
  • 341
  • 381
  • 393
  • 413
  • 417
  • 437
  • 453
  • 469
  • 473
  • 489
  • 497
  • 501
  • 517
  • 537
  • 553
  • 573
  • 581
  • 589
  • 597
  • 633
  • 649
  • 669
  • 681
  • 713
  • 717
  • 721
  • 737
  • 749
  • 753
  • 781
  • 789
  • 813
  • 817
  • 849
  • 869
  • 889
  • 893
  • 913
  • 917
  • 921
  • 933
  • 973
  • 989
  • 993
  • 1041
  • 1057
  • 1077
  • 1081
  • 1101
  • 1121
  • 1133
  • 1137
  • 1141
  • 1149
  • 1169
  • 1177
  • 1253
  • 1257
  • 1273
  • 1293
  • 1317
  • 1329
  • 1333
  • 1337
  • 1349
  • 1357
  • 1389
  • 1393
  • 1397
  • 1401
  • 1437
  • 1441
  • 1457
  • 1461
  • 1473
  • 1477
  • 1497
  • 1501