6638195840 has 64 divisors (see below), whose sum is σ = 15883180920. Its totient is φ = 2652979200.

The previous prime is 6638195803. The next prime is 6638195857. The reversal of 6638195840 is 485918366.

It can be written as a sum of positive squares in 4 ways, for example, as 5515141696 + 1123054144 = 74264^2 + 33512^2 .

It is a tau number, because it is divible by the number of its divisors (64).

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, 867230 + ... + 874850.

Almost surely, 2^6638195840 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6638195840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7941590460).

6638195840 is an abundant number, since it is smaller than the sum of its proper divisors (9244985080).

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

6638195840 is a wasteful number, since it uses less digits than its factorization.

6638195840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9001 (or 8989 counting only the distinct ones).

The product of its (nonzero) digits is 1244160, while the sum is 50.

The square root of 6638195840 is about 81475.1240563646. The cubic root of 6638195840 is about 1879.3890273584.

The spelling of 6638195840 in words is "six billion, six hundred thirty-eight million, one hundred ninety-five thousand, eight hundred forty".