639431 has 8 divisors (see below), whose sum is σ = 696864. Its totient is φ = 583200.

The previous prime is 639391. The next prime is 639433. The reversal of 639431 is 134936.

639431 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 639431 - 2¹⁸ = 377287 is a prime.

It is a super-2 number, since 2×639431² = 817744007522, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 639431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639433) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1070 + ... + 1556.

It is an arithmetic number, because the mean of its divisors is an integer number (87108).

2⁶³⁹⁴³¹ is an apocalyptic number.

639431 is a deficient number, since it is larger than the sum of its proper divisors (57433).

639431 is a wasteful number, since it uses less digits than its factorization.

639431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 601.

The product of its digits is 1944, while the sum is 26.

The square root of 639431 is about 799.6442959216. The cubic root of 639431 is about 86.1518410010.

The spelling of 639431 in words is "six hundred thirty-nine thousand, four hundred thirty-one".