638438400 has 396 divisors, whose sum is σ = 2435225832. Its totient is φ = 159252480.

The previous prime is 638438341. The next prime is 638438467. The reversal of 638438400 is 4834836.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3916719 + ... + 3916881.

Almost surely, 2^638438400 is an apocalyptic number.

638438400 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 638438400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1217612916).

638438400 is an abundant number, since it is smaller than the sum of its proper divisors (1796787432).

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

638438400 is a wasteful number, since it uses less digits than its factorization.

638438400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216 (or 190 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 638438400 is about 25267.3386014436. The cubic root of 638438400 is about 861.0723957466.

The spelling of 638438400 in words is "six hundred thirty-eight million, four hundred thirty-eight thousand, four hundred".