639135802 has 4 divisors (see below), whose sum is σ = 958703706. Its totient is φ = 319567900.

The previous prime is 639135793. The next prime is 639135803. The reversal of 639135802 is 208531936.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 637007121 + 2128681 = 25239^2 + 1459^2 .

It is not an unprimeable number, because it can be changed into a prime (639135803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159783949 + ... + 159783952.

Almost surely, 2^639135802 is an apocalyptic number.

639135802 is a deficient number, since it is larger than the sum of its proper divisors (319567904).

639135802 is a wasteful number, since it uses less digits than its factorization.

639135802 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319567903.

The product of its (nonzero) digits is 38880, while the sum is 37.

The square root of 639135802 is about 25281.1352988745. The cubic root of 639135802 is about 861.3858141778.

The spelling of 639135802 in words is "six hundred thirty-nine million, one hundred thirty-five thousand, eight hundred two".