1638385872 has 40 divisors (see below), whose sum is σ = 4276142976. Its totient is φ = 540496896.

The previous prime is 1638385843. The next prime is 1638385883. The reversal of 1638385872 is 2785838361.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 171288 + ... + 180599.

Almost surely, 2^1638385872 is an apocalyptic number.

1638385872 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1638385872 is an abundant number, since it is smaller than the sum of its proper divisors (2637757104).

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

1638385872 is a wasteful number, since it uses less digits than its factorization.

1638385872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 351995 (or 351989 counting only the distinct ones).

The product of its digits is 1935360, while the sum is 51.

The square root of 1638385872 is about 40476.9795315807. The cubic root of 1638385872 is about 1178.8866910137.

The spelling of 1638385872 in words is "one billion, six hundred thirty-eight million, three hundred eighty-five thousand, eight hundred seventy-two".