3638979891 has 24 divisors (see below), whose sum is σ = 5635689360. Its totient is φ = 2320499808.

The previous prime is 3638979871. The next prime is 3638979961. The reversal of 3638979891 is 1989798363.

It is not a de Polignac number, because 3638979891 - 2⁷ = 3638979763 is a prime.

It is not an unprimeable number, because it can be changed into a prime (3638979871) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 113106 + ... + 141671.

It is an arithmetic number, because the mean of its divisors is an integer number (234820390).

Almost surely, 2^3638979891 is an apocalyptic number.

3638979891 is a deficient number, since it is larger than the sum of its proper divisors (1996709469).

3638979891 is a wasteful number, since it uses less digits than its factorization.

3638979891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 254832 (or 254803 counting only the distinct ones).

The product of its digits is 17635968, while the sum is 63.

The square root of 3638979891 is about 60323.9578525813. The cubic root of 3638979891 is about 1538.1306224501.

The spelling of 3638979891 in words is "three billion, six hundred thirty-eight million, nine hundred seventy-nine thousand, eight hundred ninety-one".