21537889785 has 24 divisors (see below), whose sum is σ = 38242890504. Its totient is φ = 11206705920.

The previous prime is 21537889757. The next prime is 21537889799. The reversal of 21537889785 is 58798873512.

21537889785 is a `hidden beast` number, since 2 + 1 + 537 + 8 + 8 + 97 + 8 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 171636201 + 21366253584 = 13101^2 + 146172^2 .

It is not a de Polignac number, because 21537889785 - 2⁷ = 21537889657 is a prime.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 5834982 + ... + 5838671.

It is an arithmetic number, because the mean of its divisors is an integer number (1593453771).

Almost surely, 2^21537889785 is an apocalyptic number.

It is an amenable number.

21537889785 is a deficient number, since it is larger than the sum of its proper divisors (16705000719).

21537889785 is a wasteful number, since it uses less digits than its factorization.

21537889785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11673705 (or 11673702 counting only the distinct ones).

The product of its digits is 33868800, while the sum is 63.

The spelling of 21537889785 in words is "twenty-one billion, five hundred thirty-seven million, eight hundred eighty-nine thousand, seven hundred eighty-five".