639881605476 has 27 divisors (see below), whose sum is σ = 1617490635033. Its totient is φ = 213292268640.

The previous prime is 639881605459. The next prime is 639881605477. The reversal of 639881605476 is 674506188936.

The square root of 639881605476 is 799926.

It is a perfect power (a square), and thus also a powerful number.

639881605476 is a `hidden beast` number, since 6 + 3 + 9 + 8 + 81 + 6 + 0 + 547 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 570438815076 + 69442790400 = 755274^2 + 263520^2 .

It is not an unprimeable number, because it can be changed into a prime (639881605477) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 4732896 + ... + 4866216.

Almost surely, 2^639881605476 is an apocalyptic number.

639881605476 is the 799926-th square number.

It is an amenable number.

639881605476 is an abundant number, since it is smaller than the sum of its proper divisors (977609029557).

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

639881605476 is an frugal number, since it uses more digits than its factorization.

639881605476 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 266652 (or 133326 counting only the distinct ones).

The product of its (nonzero) digits is 52254720, while the sum is 63.

The spelling of 639881605476 in words is "six hundred thirty-nine billion, eight hundred eighty-one million, six hundred five thousand, four hundred seventy-six".