21968631 has 16 divisors (see below), whose sum is σ = 33669600. Its totient is φ = 14140224.

The previous prime is 21968603. The next prime is 21968633. The reversal of 21968631 is 13686912.

21968631 is a `hidden beast` number, since 2 + 19 + 6 + 8 + 631 = 666.

It is not a de Polignac number, because 21968631 - 2⁶ = 21968567 is a prime.

It is a super-2 number, since 2×21968631² = 965241496028322, which contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21968633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13246 + ... + 14811.

It is an arithmetic number, because the mean of its divisors is an integer number (2104350).

Almost surely, 2^21968631 is an apocalyptic number.

21968631 is a deficient number, since it is larger than the sum of its proper divisors (11700969).

21968631 is a wasteful number, since it uses less digits than its factorization.

21968631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28095 (or 28089 counting only the distinct ones).

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

The square root of 21968631 is about 4687.0706203342. The cubic root of 21968631 is about 280.0706921847.

The spelling of 21968631 in words is "twenty-one million, nine hundred sixty-eight thousand, six hundred thirty-one".