639442 has 8 divisors (see below), whose sum is σ = 975600. Its totient is φ = 314244.

The previous prime is 639439. The next prime is 639451. The reversal of 639442 is 244936.

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

It is a self number, because there is not a number n which added to its sum of digits gives 639442.

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, 2592 + ... + 2827.

It is an arithmetic number, because the mean of its divisors is an integer number (121950).

2⁶³⁹⁴⁴² is an apocalyptic number.

639442 is a deficient number, since it is larger than the sum of its proper divisors (336158).

639442 is a wasteful number, since it uses less digits than its factorization.

639442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5480.

The product of its digits is 5184, while the sum is 28.

The square root of 639442 is about 799.6511739502. The cubic root of 639442 is about 86.1523350157.

It can be divided in two parts, 639 and 442, that added together give a triangular number (1081 = T₄₆).

The spelling of 639442 in words is "six hundred thirty-nine thousand, four hundred forty-two".