25209 has 6 divisors (see below), whose sum is σ = 36426. Its totient is φ = 16800.

The previous prime is 25189. The next prime is 25219. The reversal of 25209 is 90252.

It can be written as a sum of positive squares in only one way, i.e., 21609 + 3600 = 147^2 + 60^2 .

It is not a de Polignac number, because 25209 - 2⁸ = 24953 is a prime.

It is a nialpdrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 25191 and 25200.

It is not an unprimeable number, because it can be changed into a prime (25219) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1392 + ... + 1409.

It is an arithmetic number, because the mean of its divisors is an integer number (6071).

2²⁵²⁰⁹ is an apocalyptic number.

It is an amenable number.

25209 is a deficient number, since it is larger than the sum of its proper divisors (11217).

25209 is a wasteful number, since it uses less digits than its factorization.

25209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2807 (or 2804 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 25209 is about 158.7734234688. The cubic root of 25209 is about 29.3214339936.

It can be divided in two parts, 25 and 209, that multiplied together give a palindrome (5225).

The spelling of 25209 in words is "twenty-five thousand, two hundred nine".