639443642 has 8 divisors (see below), whose sum is σ = 959338836. Its totient is φ = 319664032.

The previous prime is 639443639. The next prime is 639443653. The reversal of 639443642 is 246344936.

It can be written as a sum of positive squares in 2 ways, for example, as 582305161 + 57138481 = 24131^2 + 7559^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 639443642.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13403 + ... + 38190.

Almost surely, 2^639443642 is an apocalyptic number.

639443642 is a deficient number, since it is larger than the sum of its proper divisors (319895194).

639443642 is a wasteful number, since it uses less digits than its factorization.

639443642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57792.

The product of its digits is 373248, while the sum is 41.

The square root of 639443642 is about 25287.2229001130. Note that the first 3 decimals coincide. The cubic root of 639443642 is about 861.5240875811.

The spelling of 639443642 in words is "six hundred thirty-nine million, four hundred forty-three thousand, six hundred forty-two".