21696631 has 8 divisors (see below), whose sum is σ = 23866128. Its totient is φ = 19723000.

The previous prime is 21696629. The next prime is 21696707. The reversal of 21696631 is 13669612.

It is not a de Polignac number, because 21696631 - 2¹ = 21696629 is a prime.

It is a super-2 number, since 2×21696631² = 941487593500322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21690631) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6820 + ... + 9481.

It is an arithmetic number, because the mean of its divisors is an integer number (2983266).

Almost surely, 2^21696631 is an apocalyptic number.

21696631 is a deficient number, since it is larger than the sum of its proper divisors (2169497).

21696631 is an equidigital number, since it uses as much as digits as its factorization.

21696631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16334 (or 16312 counting only the distinct ones).

The product of its digits is 11664, while the sum is 34.

The square root of 21696631 is about 4657.9642549079. The cubic root of 21696631 is about 278.9100098171.

The spelling of 21696631 in words is "twenty-one million, six hundred ninety-six thousand, six hundred thirty-one".