639138946 has 8 divisors (see below), whose sum is σ = 991767420. Its totient is φ = 308549808.

The previous prime is 639138943. The next prime is 639138959. The reversal of 639138946 is 649831936.

It can be written as a sum of positive squares in 2 ways, for example, as 596092225 + 43046721 = 24415^2 + 6561^2 .

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 639138946.

It is not an unprimeable number, because it can be changed into a prime (639138943) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5509761 + ... + 5509876.

Almost surely, 2^639138946 is an apocalyptic number.

639138946 is a deficient number, since it is larger than the sum of its proper divisors (352628474).

639138946 is a wasteful number, since it uses less digits than its factorization.

639138946 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11019668.

The product of its digits is 839808, while the sum is 49.

The square root of 639138946 is about 25281.1974795499. The cubic root of 639138946 is about 861.3872266020.

The spelling of 639138946 in words is "six hundred thirty-nine million, one hundred thirty-eight thousand, nine hundred forty-six".