639855455 has 4 divisors (see below), whose sum is σ = 767826552. Its totient is φ = 511884360.

The previous prime is 639855431. The next prime is 639855473. The reversal of 639855455 is 554558936.

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

It is not a de Polignac number, because 639855455 - 2⁸ = 639855199 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63985541 + ... + 63985550.

It is an arithmetic number, because the mean of its divisors is an integer number (191956638).

Almost surely, 2^639855455 is an apocalyptic number.

639855455 is a deficient number, since it is larger than the sum of its proper divisors (127971097).

639855455 is a wasteful number, since it uses less digits than its factorization.

639855455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127971096.

The product of its digits is 3240000, while the sum is 50.

The square root of 639855455 is about 25295.3642986220. The cubic root of 639855455 is about 861.7089934691.

The spelling of 639855455 in words is "six hundred thirty-nine million, eight hundred fifty-five thousand, four hundred fifty-five".