3638638665 has 20 divisors (see below), whose sum is σ = 6522597444. Its totient is φ = 1940607072.

The previous prime is 3638638573. The next prime is 3638638691. The reversal of 3638638665 is 5668368363.

It can be written as a sum of positive squares in 2 ways, for example, as 2747437056 + 891201609 = 52416^2 + 29853^2 .

It is not a de Polignac number, because 3638638665 - 2²² = 3634444361 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 4491742 + ... + 4492551.

Almost surely, 2^3638638665 is an apocalyptic number.

It is an amenable number.

3638638665 is a deficient number, since it is larger than the sum of its proper divisors (2883958779).

3638638665 is an equidigital number, since it uses as much as digits as its factorization.

3638638665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8984310 (or 8984301 counting only the distinct ones).

The product of its digits is 11197440, while the sum is 54.

The square root of 3638638665 is about 60321.1295069978. The cubic root of 3638638665 is about 1538.0825442724.

The spelling of 3638638665 in words is "three billion, six hundred thirty-eight million, six hundred thirty-eight thousand, six hundred sixty-five".