21561625635 has 16 divisors (see below), whose sum is σ = 37634837760. Its totient is φ = 10454121440.

The previous prime is 21561625633. The next prime is 21561625681. The reversal of 21561625635 is 53652616512.

It is not a de Polignac number, because 21561625635 - 2¹ = 21561625633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21561625633) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 65338095 + ... + 65338424.

It is an arithmetic number, because the mean of its divisors is an integer number (2352177360).

Almost surely, 2^21561625635 is an apocalyptic number.

21561625635 is a deficient number, since it is larger than the sum of its proper divisors (16073212125).

21561625635 is a wasteful number, since it uses less digits than its factorization.

21561625635 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130676538.

The product of its digits is 324000, while the sum is 42.

The spelling of 21561625635 in words is "twenty-one billion, five hundred sixty-one million, six hundred twenty-five thousand, six hundred thirty-five".