21610931 has 2 divisors, whose sum is σ = 21610932. Its totient is φ = 21610930.

The previous prime is 21610913. The next prime is 21610943. The reversal of 21610931 is 13901612.

It is a happy number.

Together with previous prime (21610913) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21610931 - 2²² = 17416627 is a prime.

It is a super-2 number, since 2×21610931² = 934064677373522, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21610897 and 21610906.

It is not a weakly prime, because it can be changed into another prime (21610991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10805465 + 10805466.

It is an arithmetic number, because the mean of its divisors is an integer number (10805466).

Almost surely, 2^21610931 is an apocalyptic number.

21610931 is a deficient number, since it is larger than the sum of its proper divisors (1).

21610931 is an equidigital number, since it uses as much as digits as its factorization.

21610931 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 21610931 is about 4648.7558550649. The cubic root of 21610931 is about 278.5423009901.

The spelling of 21610931 in words is "twenty-one million, six hundred ten thousand, nine hundred thirty-one".