Compare 2 vs 21

Unique factors12
Total factors12
Prime factorization2131 × 71
Prime factorization23 × 7
Divisors count24
Divisors1, 21, 3, 7, 21
Number of properties261
Additive primes1st 
Bell primes1st 
Chen primes1st 
Class 1+ primes1st 
Dihedral primes1st 
Euclid primes1st 
Factorial primes1st 
Fibonacci primes1st 
Isolated primes1st 
Kynea primes1st 
Left-truncatable primes1st 
Lucas primes1st 
Mills primes1st 
Multiplicative primes1st 
Palindromic primes1st 
Pierpont primes1st 
Pierpont primes of the 2nd kind1st 
Quartan primes1st 
Restricted left-truncatable primes1st 
Right-truncatable primes1st 
Semiprimes 7th
Sophie germain primes1st 
Thabit primes1st 
Two-sided primes1st 
Ulam primes1st 
Wedderburn-etherington primes1st 
Roman numberalsIIXXI
Base 2102101012
Base 3232103
Base 4241114
Base 525415
Base 626336
Base 727307
Base 828258
Base 929239
Base 102102110
Base 112111a11
Base 122121912
Base 132131813
Base 142141714
Base 152151615
Base 162161516
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