21257984 has 36 divisors (see below), whose sum is σ = 46296600. Its totient is φ = 9661440.

The previous prime is 21257969. The next prime is 21257993. The reversal of 21257984 is 48975212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 959 + ... + 6590.

Almost surely, 2^21257984 is an apocalyptic number.

It is an amenable number.

21257984 is an abundant number, since it is smaller than the sum of its proper divisors (25038616).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21257984 is an equidigital number, since it uses as much as digits as its factorization.

21257984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7576 (or 7562 counting only the distinct ones).

The product of its digits is 40320, while the sum is 38.

The square root of 21257984 is about 4610.6381337077. The cubic root of 21257984 is about 277.0175976170.

The spelling of 21257984 in words is "twenty-one million, two hundred fifty-seven thousand, nine hundred eighty-four".