21085157538 has 12 divisors (see below), whose sum is σ = 45684508038. Its totient is φ = 7028385840.

The previous prime is 21085157537. The next prime is 21085157567. The reversal of 21085157538 is 83575158012.

21085157538 is a `hidden beast` number, since 2 + 10 + 8 + 51 + 57 + 538 = 666.

It can be written as a sum of positive squares in only one way, i.e., 13168251009 + 7916906529 = 114753^2 + 88977^2 .

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21085157493 and 21085157502.

It is not an unprimeable number, because it can be changed into a prime (21085157537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 585698803 + ... + 585698838.

Almost surely, 2^21085157538 is an apocalyptic number.

21085157538 is an abundant number, since it is smaller than the sum of its proper divisors (24599350500).

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

21085157538 is a wasteful number, since it uses less digits than its factorization.

21085157538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1171397649 (or 1171397646 counting only the distinct ones).

The product of its (nonzero) digits is 336000, while the sum is 45.

The spelling of 21085157538 in words is "twenty-one billion, eighty-five million, one hundred fifty-seven thousand, five hundred thirty-eight".