639525 has 12 divisors (see below), whose sum is σ = 1057472. Its totient is φ = 341040.

The previous prime is 639517. The next prime is 639533. The reversal of 639525 is 525936.

It is an interprime number because it is at equal distance from previous prime (639517) and next prime (639533).

It is not a de Polignac number, because 639525 - 2³ = 639517 is a prime.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 639492 and 639501.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4189 + ... + 4338.

2⁶³⁹⁵²⁵ is an apocalyptic number.

It is an amenable number.

639525 is a deficient number, since it is larger than the sum of its proper divisors (417947).

639525 is a wasteful number, since it uses less digits than its factorization.

639525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8540 (or 8535 counting only the distinct ones).

The product of its digits is 8100, while the sum is 30.

The square root of 639525 is about 799.7030698953. The cubic root of 639525 is about 86.1560623980.

The spelling of 639525 in words is "six hundred thirty-nine thousand, five hundred twenty-five".