21877012800 has 126 divisors (see below), whose sum is σ = 77756120078. Its totient is φ = 5833866240.

The previous prime is 21877012799. The next prime is 21877012823. The reversal of 21877012800 is 821077812.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 211527936 + 21665484864 = 14544^2 + 147192^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

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 17 ways as a sum of consecutive naturals, for example, 745219 + ... + 774018.

Almost surely, 2^21877012800 is an apocalyptic number.

21877012800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21877012800 is an abundant number, since it is smaller than the sum of its proper divisors (55879107278).

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

21877012800 is a wasteful number, since it uses less digits than its factorization.

21877012800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1519265 (or 1519247 counting only the distinct ones).

The product of its (nonzero) digits is 12544, while the sum is 36.

It can be divided in two parts, 21877012 and 800, that added together give a palindrome (21877812).

The spelling of 21877012800 in words is "twenty-one billion, eight hundred seventy-seven million, twelve thousand, eight hundred".