21531976 has 16 divisors (see below), whose sum is σ = 40425840. Its totient is φ = 10751760.

The previous prime is 21531973. The next prime is 21531977. The reversal of 21531976 is 67913512.

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 3 ways as a sum of consecutive naturals, for example, 7495 + ... + 9961.

It is an arithmetic number, because the mean of its divisors is an integer number (2526615).

Almost surely, 2^21531976 is an apocalyptic number.

It is an amenable number.

21531976 is a deficient number, since it is larger than the sum of its proper divisors (18893864).

21531976 is a wasteful number, since it uses less digits than its factorization.

21531976 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3564 (or 3560 counting only the distinct ones).

The product of its digits is 11340, while the sum is 34.

The square root of 21531976 is about 4640.2560274192. The cubic root of 21531976 is about 278.2026712497.

The spelling of 21531976 in words is "twenty-one million, five hundred thirty-one thousand, nine hundred seventy-six".