639279128 has 8 divisors (see below), whose sum is σ = 1198648380. Its totient is φ = 319639560.

The previous prime is 639279119. The next prime is 639279131. The reversal of 639279128 is 821972936.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39954938 + ... + 39954953.

Almost surely, 2^639279128 is an apocalyptic number.

It is an amenable number.

639279128 is a deficient number, since it is larger than the sum of its proper divisors (559369252).

639279128 is a wasteful number, since it uses less digits than its factorization.

639279128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79909897 (or 79909893 counting only the distinct ones).

The product of its digits is 326592, while the sum is 47.

The square root of 639279128 is about 25283.9697832441. The cubic root of 639279128 is about 861.4501978635.

The spelling of 639279128 in words is "six hundred thirty-nine million, two hundred seventy-nine thousand, one hundred twenty-eight".