21255611156 has 48 divisors (see below), whose sum is σ = 43783326720. Its totient is φ = 8935349760.

The previous prime is 21255611147. The next prime is 21255611189. The reversal of 21255611156 is 65111655212.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 360416 + ... + 415223.

It is an arithmetic number, because the mean of its divisors is an integer number (912152640).

Almost surely, 2^21255611156 is an apocalyptic number.

21255611156 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21255611156 is an abundant number, since it is smaller than the sum of its proper divisors (22527715564).

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

21255611156 is a wasteful number, since it uses less digits than its factorization.

21255611156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 775704 (or 775702 counting only the distinct ones).

The product of its digits is 18000, while the sum is 35.

The spelling of 21255611156 in words is "twenty-one billion, two hundred fifty-five million, six hundred eleven thousand, one hundred fifty-six".