21780942624 has 72 divisors (see below), whose sum is σ = 70788070080. Its totient is φ = 6223125888.

The previous prime is 21780942553. The next prime is 21780942637. The reversal of 21780942624 is 42624908712.

21780942624 is a `hidden beast` number, since 2 + 17 + 8 + 0 + 9 + 4 + 2 + 624 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a self number, because there is not a number n which added to its sum of digits gives 21780942624.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5400004 + ... + 5404035.

It is an arithmetic number, because the mean of its divisors is an integer number (983167640).

Almost surely, 2^21780942624 is an apocalyptic number.

21780942624 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21780942624 is an abundant number, since it is smaller than the sum of its proper divisors (49007127456).

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

21780942624 is a wasteful number, since it uses less digits than its factorization.

21780942624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10804062 (or 10804051 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 45.

The spelling of 21780942624 in words is "twenty-one billion, seven hundred eighty million, nine hundred forty-two thousand, six hundred twenty-four".