21531974 has 12 divisors (see below), whose sum is σ = 32623044. Its totient is φ = 10658304.

The previous prime is 21531973. The next prime is 21531977. The reversal of 21531974 is 47913512.

It is a self number, because there is not a number n which added to its sum of digits gives 21531974.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531973) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 83654 + ... + 83910.

It is an arithmetic number, because the mean of its divisors is an integer number (2718587).

Almost surely, 2^21531974 is an apocalyptic number.

21531974 is a deficient number, since it is larger than the sum of its proper divisors (11091070).

21531974 is an equidigital number, since it uses as much as digits as its factorization.

21531974 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 679 (or 422 counting only the distinct ones).

The product of its digits is 7560, while the sum is 32.

The square root of 21531974 is about 4640.2558119138. The cubic root of 21531974 is about 278.2026626361.

The spelling of 21531974 in words is "twenty-one million, five hundred thirty-one thousand, nine hundred seventy-four".