639091772 has 12 divisors (see below), whose sum is σ = 1220084376. Its totient is φ = 290496240.

The previous prime is 639091769. The next prime is 639091807. The reversal of 639091772 is 277190936.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (44), and also a Moran number because the ratio is a prime number: 14524813 = 639091772 / (6 + 3 + 9 + 0 + 9 + 1 + 7 + 7 + 2).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7262363 + ... + 7262450.

It is an arithmetic number, because the mean of its divisors is an integer number (101673698).

Almost surely, 2^639091772 is an apocalyptic number.

It is an amenable number.

639091772 is a deficient number, since it is larger than the sum of its proper divisors (580992604).

639091772 is a wasteful number, since it uses less digits than its factorization.

639091772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14524828 (or 14524826 counting only the distinct ones).

The product of its (nonzero) digits is 142884, while the sum is 44.

The square root of 639091772 is about 25280.2644764646. The cubic root of 639091772 is about 861.3660334634.

The spelling of 639091772 in words is "six hundred thirty-nine million, ninety-one thousand, seven hundred seventy-two".