21657602728 has 16 divisors (see below), whose sum is σ = 40610858580. Its totient is φ = 10828040448.

The previous prime is 21657602719. The next prime is 21657602749. The reversal of 21657602728 is 82720675612.

It can be written as a sum of positive squares in 2 ways, for example, as 21655476964 + 2125764 = 147158^2 + 1458^2 .

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, 36576 + ... + 211312.

Almost surely, 2^21657602728 is an apocalyptic number.

It is an amenable number.

21657602728 is a deficient number, since it is larger than the sum of its proper divisors (18953255852).

21657602728 is a wasteful number, since it uses less digits than its factorization.

21657602728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190236 (or 190232 counting only the distinct ones).

The product of its (nonzero) digits is 564480, while the sum is 46.

The spelling of 21657602728 in words is "twenty-one billion, six hundred fifty-seven million, six hundred two thousand, seven hundred twenty-eight".