21938631 has 24 divisors (see below), whose sum is σ = 34633200. Its totient is φ = 12270720.

The previous prime is 21938629. The next prime is 21938633. The reversal of 21938631 is 13683912.

It is an interprime number because it is at equal distance from previous prime (21938629) and next prime (21938633).

It is not a de Polignac number, because 21938631 - 2¹ = 21938629 is a prime.

It is a super-2 number, since 2×21938631² = 962607060308322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a junction number, because it is equal to n+sod(n) for n = 21938592 and 21938601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21938633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2395 + ... + 7043.

It is an arithmetic number, because the mean of its divisors is an integer number (1443050).

Almost surely, 2^21938631 is an apocalyptic number.

21938631 is a deficient number, since it is larger than the sum of its proper divisors (12694569).

21938631 is a wasteful number, since it uses less digits than its factorization.

21938631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4687 (or 4676 counting only the distinct ones).

The product of its digits is 7776, while the sum is 33.

The square root of 21938631 is about 4683.8692338706. The cubic root of 21938631 is about 279.9431474708.

The spelling of 21938631 in words is "twenty-one million, nine hundred thirty-eight thousand, six hundred thirty-one".