639766 has 4 divisors (see below), whose sum is σ = 959652. Its totient is φ = 319882.

The previous prime is 639757. The next prime is 639833. The reversal of 639766 is 667936.

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

It is a nialpdrome in base 15.

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, 159940 + ... + 159943.

It is an arithmetic number, because the mean of its divisors is an integer number (239913).

2⁶³⁹⁷⁶⁶ is an apocalyptic number.

639766 is a deficient number, since it is larger than the sum of its proper divisors (319886).

639766 is a wasteful number, since it uses less digits than its factorization.

639766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319885.

The product of its digits is 40824, while the sum is 37.

The square root of 639766 is about 799.8537366294. The cubic root of 639766 is about 86.1668834519.

The spelling of 639766 in words is "six hundred thirty-nine thousand, seven hundred sixty-six".