21657004 has 12 divisors (see below), whose sum is σ = 37961728. Its totient is φ = 10810800.

The previous prime is 21656977. The next prime is 21657011. The reversal of 21657004 is 40075612.

It is a self number, because there is not a number n which added to its sum of digits gives 21657004.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 1452 + ... + 6739.

Almost surely, 2^21657004 is an apocalyptic number.

It is an amenable number.

21657004 is a deficient number, since it is larger than the sum of its proper divisors (16304724).

21657004 is a wasteful number, since it uses less digits than its factorization.

21657004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8856 (or 8854 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 21657004 is about 4653.7086286101. The cubic root of 21657004 is about 278.7401047517.

The spelling of 21657004 in words is "twenty-one million, six hundred fifty-seven thousand, four".