18821657664 has 140 divisors (see below), whose sum is σ = 55868756944. Its totient is φ = 6265403136.

The previous prime is 18821657641. The next prime is 18821657693. The reversal of 18821657664 is 46675612881.

18821657664 is a `hidden beast` number, since 1 + 8 + 8 + 2 + 1 + 6 + 576 + 64 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 18821657664.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 4699887 + ... + 4703889.

Almost surely, 2^18821657664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18821657664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27934378472).

18821657664 is an abundant number, since it is smaller than the sum of its proper divisors (37047099280).

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

18821657664 is an equidigital number, since it uses as much as digits as its factorization.

18821657664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4934 (or 4915 counting only the distinct ones).

The product of its digits is 3870720, while the sum is 54.

The spelling of 18821657664 in words is "eighteen billion, eight hundred twenty-one million, six hundred fifty-seven thousand, six hundred sixty-four".