21102931 has 2 divisors, whose sum is σ = 21102932. Its totient is φ = 21102930.

The previous prime is 21102919. The next prime is 21102941. The reversal of 21102931 is 13920112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21102931 - 2¹⁹ = 20578643 is a prime.

It is a super-2 number, since 2×21102931² = 890667393581522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21102899 and 21102908.

It is not a weakly prime, because it can be changed into another prime (21102911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551465 + 10551466.

It is an arithmetic number, because the mean of its divisors is an integer number (10551466).

Almost surely, 2^21102931 is an apocalyptic number.

21102931 is a deficient number, since it is larger than the sum of its proper divisors (1).

21102931 is an equidigital number, since it uses as much as digits as its factorization.

21102931 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108, while the sum is 19.

The square root of 21102931 is about 4593.7926596659. The cubic root of 21102931 is about 276.3424432125.

It can be divided in two parts, 2110 and 2931, that added together give a square (5041 = 71²).

The spelling of 21102931 in words is "twenty-one million, one hundred two thousand, nine hundred thirty-one".