639722 has 8 divisors (see below), whose sum is σ = 1001376. Its totient is φ = 305932.

The previous prime is 639719. The next prime is 639731. The reversal of 639722 is 227936.

639722 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a nialpdrome in base 15.

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, 6908 + ... + 6999.

It is an arithmetic number, because the mean of its divisors is an integer number (125172).

2⁶³⁹⁷²² is an apocalyptic number.

639722 is a deficient number, since it is larger than the sum of its proper divisors (361654).

639722 is a wasteful number, since it uses less digits than its factorization.

639722 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13932.

The product of its digits is 4536, while the sum is 29.

The square root of 639722 is about 799.8262311277. The cubic root of 639722 is about 86.1649080266.

The spelling of 639722 in words is "six hundred thirty-nine thousand, seven hundred twenty-two".