21986631 has 12 divisors (see below), whose sum is σ = 32497608. Its totient is φ = 14316624.

The previous prime is 21986623. The next prime is 21986639. The reversal of 21986631 is 13668912.

21986631 is a `hidden beast` number, since 2 + 19 + 8 + 6 + 631 = 666.

It is an interprime number because it is at equal distance from previous prime (21986623) and next prime (21986639).

It is not a de Polignac number, because 21986631 - 2³ = 21986623 is a prime.

It is a super-2 number, since 2×21986631² = 966823885460322, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21986639) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 28020 + ... + 28793.

It is an arithmetic number, because the mean of its divisors is an integer number (2708134).

Almost surely, 2^21986631 is an apocalyptic number.

21986631 is a deficient number, since it is larger than the sum of its proper divisors (10510977).

21986631 is a wasteful number, since it uses less digits than its factorization.

21986631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56862 (or 56859 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 21986631 is about 4688.9904030612. The cubic root of 21986631 is about 280.1471632862.

The spelling of 21986631 in words is "twenty-one million, nine hundred eighty-six thousand, six hundred thirty-one".