639557774 has 4 divisors (see below), whose sum is σ = 959336664. Its totient is φ = 319778886.

The previous prime is 639557773. The next prime is 639557777. The reversal of 639557774 is 477755936.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639557773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159889442 + ... + 159889445.

It is an arithmetic number, because the mean of its divisors is an integer number (239834166).

Almost surely, 2^639557774 is an apocalyptic number.

639557774 is a deficient number, since it is larger than the sum of its proper divisors (319778890).

639557774 is a wasteful number, since it uses less digits than its factorization.

639557774 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319778889.

The product of its digits is 5556600, while the sum is 53.

The square root of 639557774 is about 25289.4795122399. The cubic root of 639557774 is about 861.5753413123.

The spelling of 639557774 in words is "six hundred thirty-nine million, five hundred fifty-seven thousand, seven hundred seventy-four".