25639 has 2 divisors, whose sum is σ = 25640. Its totient is φ = 25638.

The previous prime is 25633. The next prime is 25643. The reversal of 25639 is 93652.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 25639 - 2⁹ = 25127 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12819 + 12820.

It is an arithmetic number, because the mean of its divisors is an integer number (12820).

2²⁵⁶³⁹ is an apocalyptic number.

25639 is a deficient number, since it is larger than the sum of its proper divisors (1).

25639 is an equidigital number, since it uses as much as digits as its factorization.

25639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1620, while the sum is 25.

The square root of 25639 is about 160.1218286181. The cubic root of 25639 is about 29.4872107734.

The spelling of 25639 in words is "twenty-five thousand, six hundred thirty-nine".