639479 has 4 divisors (see below), whose sum is σ = 661560. Its totient is φ = 617400.

The previous prime is 639451. The next prime is 639487. The reversal of 639479 is 974936.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639479 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 (639439) 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, 10997 + ... + 11054.

It is an arithmetic number, because the mean of its divisors is an integer number (165390).

2⁶³⁹⁴⁷⁹ is an apocalyptic number.

639479 is a deficient number, since it is larger than the sum of its proper divisors (22081).

639479 is a wasteful number, since it uses less digits than its factorization.

639479 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22080.

The product of its digits is 40824, while the sum is 38.

The square root of 639479 is about 799.6743087032. The cubic root of 639479 is about 86.1539966597.

The spelling of 639479 in words is "six hundred thirty-nine thousand, four hundred seventy-nine".