639425 has 6 divisors (see below), whose sum is σ = 792918. Its totient is φ = 511520.

The previous prime is 639391. The next prime is 639433. The reversal of 639425 is 524936.

It can be written as a sum of positive squares in 3 ways, for example, as 1024 + 638401 = 32^2 + 799^2 .

It is not a de Polignac number, because 639425 - 2⁶ = 639361 is a prime.

It is a d-powerful number, because it can be written as 6³ + 3⁹ + 4⁷ + 9³ + 2¹⁹ + 5⁷ .

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 639425.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12764 + ... + 12813.

It is an arithmetic number, because the mean of its divisors is an integer number (132153).

2⁶³⁹⁴²⁵ is an apocalyptic number.

It is an amenable number.

639425 is a deficient number, since it is larger than the sum of its proper divisors (153493).

639425 is a wasteful number, since it uses less digits than its factorization.

639425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25587 (or 25582 counting only the distinct ones).

The product of its digits is 6480, while the sum is 29.

The square root of 639425 is about 799.6405442447. The cubic root of 639425 is about 86.1515715361.

The spelling of 639425 in words is "six hundred thirty-nine thousand, four hundred twenty-five".