21251903 has 2 divisors, whose sum is σ = 21251904. Its totient is φ = 21251902.

The previous prime is 21251897. The next prime is 21251929. The reversal of 21251903 is 30915212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21251903 - 2¹⁶ = 21186367 is a prime.

It is a super-2 number, since 2×21251903² = 903286762242818, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21251803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625951 + 10625952.

It is an arithmetic number, because the mean of its divisors is an integer number (10625952).

Almost surely, 2^21251903 is an apocalyptic number.

21251903 is a deficient number, since it is larger than the sum of its proper divisors (1).

21251903 is an equidigital number, since it uses as much as digits as its factorization.

21251903 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 21251903 is about 4609.9786333561. The cubic root of 21251903 is about 276.9911808024.

The spelling of 21251903 in words is "twenty-one million, two hundred fifty-one thousand, nine hundred three".