18921164544 has 360 divisors, whose sum is σ = 59624869920. Its totient is φ = 5956042752.

The previous prime is 18921164531. The next prime is 18921164551. The reversal of 18921164544 is 44546112981.

18921164544 is a `hidden beast` number, since 1 + 8 + 92 + 1 + 16 + 4 + 544 = 666.

It is a super-2 number, since 2×18921164544² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 18921164544.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 46261812 + ... + 46262220.

Almost surely, 2^18921164544 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 18921164544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29812434960).

18921164544 is an abundant number, since it is smaller than the sum of its proper divisors (40703705376).

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

18921164544 is an equidigital number, since it uses as much as digits as its factorization.

18921164544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 557 (or 534 counting only the distinct ones).

The product of its digits is 276480, while the sum is 45.

The spelling of 18921164544 in words is "eighteen billion, nine hundred twenty-one million, one hundred sixty-four thousand, five hundred forty-four".