21861311636 has 24 divisors (see below), whose sum is σ = 40531780800. Its totient is φ = 10281566592.

The previous prime is 21861311629. The next prime is 21861311683. The reversal of 21861311636 is 63611316812.

It is a self number, because there is not a number n which added to its sum of digits gives 21861311636.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 20921 + ... + 210143.

It is an arithmetic number, because the mean of its divisors is an integer number (1688824200).

Almost surely, 2^21861311636 is an apocalyptic number.

It is an amenable number.

21861311636 is a deficient number, since it is larger than the sum of its proper divisors (18670469164).

21861311636 is a wasteful number, since it uses less digits than its factorization.

21861311636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190943 (or 190941 counting only the distinct ones).

The product of its digits is 31104, while the sum is 38.

The spelling of 21861311636 in words is "twenty-one billion, eight hundred sixty-one million, three hundred eleven thousand, six hundred thirty-six".