639779117 has 4 divisors (see below), whose sum is σ = 646374876. Its totient is φ = 633183360.

The previous prime is 639779113. The next prime is 639779123. The reversal of 639779117 is 711977936.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 212984836 + 426794281 = 14594^2 + 20659^2 .

It is a cyclic number.

It is not a de Polignac number, because 639779117 - 2² = 639779113 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639779111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3297734 + ... + 3297927.

It is an arithmetic number, because the mean of its divisors is an integer number (161593719).

Almost surely, 2^639779117 is an apocalyptic number.

It is an amenable number.

639779117 is a deficient number, since it is larger than the sum of its proper divisors (6595759).

639779117 is an equidigital number, since it uses as much as digits as its factorization.

639779117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6595758.

The product of its digits is 500094, while the sum is 50.

The square root of 639779117 is about 25293.8553210063. The cubic root of 639779117 is about 861.6747233555.

The spelling of 639779117 in words is "six hundred thirty-nine million, seven hundred seventy-nine thousand, one hundred seventeen".