639664775 has 12 divisors (see below), whose sum is σ = 811631832. Its totient is φ = 499830240.

The previous prime is 639664741. The next prime is 639664777. The reversal of 639664775 is 577466936.

It is not a de Polignac number, because 639664775 - 2¹⁴ = 639648391 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 (639664777) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 296444 + ... + 298593.

It is an arithmetic number, because the mean of its divisors is an integer number (67635986).

Almost surely, 2^639664775 is an apocalyptic number.

639664775 is a deficient number, since it is larger than the sum of its proper divisors (171967057).

639664775 is a wasteful number, since it uses less digits than its factorization.

639664775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 595090 (or 595085 counting only the distinct ones).

The product of its digits is 5715360, while the sum is 53.

The square root of 639664775 is about 25291.5949477292. The cubic root of 639664775 is about 861.6233871580.

The spelling of 639664775 in words is "six hundred thirty-nine million, six hundred sixty-four thousand, seven hundred seventy-five".