638608940 has 12 divisors (see below), whose sum is σ = 1341078816. Its totient is φ = 255443568.

The previous prime is 638608877. The next prime is 638608967. The reversal of 638608940 is 49806836.

It is a junction number, because it is equal to n+sod(n) for n = 638608891 and 638608900.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15965204 + ... + 15965243.

It is an arithmetic number, because the mean of its divisors is an integer number (111756568).

Almost surely, 2^638608940 is an apocalyptic number.

It is an amenable number.

638608940 is an abundant number, since it is smaller than the sum of its proper divisors (702469876).

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

638608940 is a wasteful number, since it uses less digits than its factorization.

638608940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31930456 (or 31930454 counting only the distinct ones).

The product of its (nonzero) digits is 248832, while the sum is 44.

The square root of 638608940 is about 25270.7130884746. The cubic root of 638608940 is about 861.1490589574.

The spelling of 638608940 in words is "six hundred thirty-eight million, six hundred eight thousand, nine hundred forty".