638723387904 has 480 divisors, whose sum is σ = 2079401195520. Its totient is φ = 170617135104.

The previous prime is 638723387873. The next prime is 638723387933. The reversal of 638723387904 is 409783327836.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 306635247 + ... + 306637329.

It is an arithmetic number, because the mean of its divisors is an integer number (4332085824).

Almost surely, 2^638723387904 is an apocalyptic number.

638723387904 is a gapful number since it is divisible by the number (64) 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 638723387904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1039700597760).

638723387904 is an abundant number, since it is smaller than the sum of its proper divisors (1440677807616).

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

638723387904 is a wasteful number, since it uses less digits than its factorization.

638723387904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2228 (or 2193 counting only the distinct ones).

The product of its (nonzero) digits is 36578304, while the sum is 60.

The spelling of 638723387904 in words is "six hundred thirty-eight billion, seven hundred twenty-three million, three hundred eighty-seven thousand, nine hundred four".