639478 has 8 divisors (see below), whose sum is σ = 1096272. Its totient is φ = 274056.

The previous prime is 639451. The next prime is 639487. The reversal of 639478 is 874936.

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

It is a super-2 number, since 2×639478² = 817864224968, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22825 + ... + 22852.

It is an arithmetic number, because the mean of its divisors is an integer number (137034).

2⁶³⁹⁴⁷⁸ is an apocalyptic number.

639478 is a deficient number, since it is larger than the sum of its proper divisors (456794).

639478 is a wasteful number, since it uses less digits than its factorization.

639478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45686.

The product of its digits is 36288, while the sum is 37.

The square root of 639478 is about 799.6736834484. The cubic root of 639478 is about 86.1539517512.

The spelling of 639478 in words is "six hundred thirty-nine thousand, four hundred seventy-eight".