638807504400 has 600 divisors, whose sum is σ = 2598964072320. Its totient is φ = 148967009280.

The previous prime is 638807504369. The next prime is 638807504407. The reversal of 638807504400 is 4405708836.

638807504400 is a `hidden beast` number, since 63 + 8 + 80 + 7 + 504 + 4 + 0 + 0 = 666.

638807504400 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (600).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (638807504407) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 7962889 + ... + 8042711.

Almost surely, 2^638807504400 is an apocalyptic number.

638807504400 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638807504400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1299482036160).

638807504400 is an abundant number, since it is smaller than the sum of its proper divisors (1960156567920).

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

638807504400 is a wasteful number, since it uses less digits than its factorization.

638807504400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79885 (or 79865 counting only the distinct ones).

The product of its (nonzero) digits is 645120, while the sum is 45.

The spelling of 638807504400 in words is "six hundred thirty-eight billion, eight hundred seven million, five hundred four thousand, four hundred".