21657133557 has 12 divisors (see below), whose sum is σ = 31289107200. Its totient is φ = 14435051688.

The previous prime is 21657133517. The next prime is 21657133601. The reversal of 21657133557 is 75533175612.

21657133557 is a `hidden beast` number, since 2 + 1 + 65 + 7 + 1 + 33 + 557 = 666.

It is not a de Polignac number, because 21657133557 - 2¹⁵ = 21657100789 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21657133517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 207523 + ... + 293904.

It is an arithmetic number, because the mean of its divisors is an integer number (2607425600).

Almost surely, 2^21657133557 is an apocalyptic number.

It is an amenable number.

21657133557 is a deficient number, since it is larger than the sum of its proper divisors (9631973643).

21657133557 is a wasteful number, since it uses less digits than its factorization.

21657133557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 506232 (or 506229 counting only the distinct ones).

The product of its digits is 661500, while the sum is 45.

The spelling of 21657133557 in words is "twenty-one billion, six hundred fifty-seven million, one hundred thirty-three thousand, five hundred fifty-seven".