639490 has 8 divisors (see below), whose sum is σ = 1151100. Its totient is φ = 255792.

The previous prime is 639487. The next prime is 639491. The reversal of 639490 is 94936.

It can be written as a sum of positive squares in 2 ways, for example, as 638401 + 1089 = 799^2 + 33^2 .

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

It is not an unprimeable number, because it can be changed into a prime (639491) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31965 + ... + 31984.

2⁶³⁹⁴⁹⁰ is an apocalyptic number.

639490 is a deficient number, since it is larger than the sum of its proper divisors (511610).

639490 is a wasteful number, since it uses less digits than its factorization.

639490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63956.

The product of its (nonzero) digits is 5832, while the sum is 31.

The square root of 639490 is about 799.6811864737. The cubic root of 639490 is about 86.1544906496.

The spelling of 639490 in words is "six hundred thirty-nine thousand, four hundred ninety".