639742 has 8 divisors (see below), whose sum is σ = 972000. Its totient is φ = 315744.

The previous prime is 639739. The next prime is 639757. The reversal of 639742 is 247936.

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

It is a congruent number.

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, 1867 + ... + 2182.

It is an arithmetic number, because the mean of its divisors is an integer number (121500).

2⁶³⁹⁷⁴² is an apocalyptic number.

639742 is a deficient number, since it is larger than the sum of its proper divisors (332258).

639742 is a wasteful number, since it uses less digits than its factorization.

639742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4130.

The product of its digits is 9072, while the sum is 31.

The square root of 639742 is about 799.8387337457. The cubic root of 639742 is about 86.1658059584.

The spelling of 639742 in words is "six hundred thirty-nine thousand, seven hundred forty-two".