639746626 has 4 divisors (see below), whose sum is σ = 959619942. Its totient is φ = 319873312.

The previous prime is 639746603. The next prime is 639746629. The reversal of 639746626 is 626647936.

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

It can be written as a sum of positive squares in only one way, i.e., 429525625 + 210221001 = 20725^2 + 14499^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 639746626.

It is not an unprimeable number, because it can be changed into a prime (639746629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159936655 + ... + 159936658.

Almost surely, 2^639746626 is an apocalyptic number.

639746626 is a deficient number, since it is larger than the sum of its proper divisors (319873316).

639746626 is a wasteful number, since it uses less digits than its factorization.

639746626 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319873315.

The product of its digits is 1959552, while the sum is 49.

The square root of 639746626 is about 25293.2130422372. The cubic root of 639746626 is about 861.6601364736.

The spelling of 639746626 in words is "six hundred thirty-nine million, seven hundred forty-six thousand, six hundred twenty-six".