18718520400 has 90 divisors (see below), whose sum is σ = 64958477870. Its totient is φ = 4991604480.

The previous prime is 18718520393. The next prime is 18718520417. The reversal of 18718520400 is 402581781.

18718520400 is a `hidden beast` number, since 1 + 87 + 18 + 520 + 40 + 0 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 220344336 + 18498176064 = 14844^2 + 136008^2 .

It is a tau number, because it is divible by the number of its divisors (90).

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 polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 2596195 + ... + 2603394.

Almost surely, 2^18718520400 is an apocalyptic number.

18718520400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18718520400 is an abundant number, since it is smaller than the sum of its proper divisors (46239957470).

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

18718520400 is a wasteful number, since it uses less digits than its factorization.

18718520400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5199613 (or 5199599 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 36.

The spelling of 18718520400 in words is "eighteen billion, seven hundred eighteen million, five hundred twenty thousand, four hundred".