25815 has 8 divisors (see below), whose sum is σ = 41328. Its totient is φ = 13760.

The previous prime is 25801. The next prime is 25819. The reversal of 25815 is 51852.

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

It is not a de Polignac number, because 25815 - 2⁴ = 25799 is a prime.

25815 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 25791 and 25800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25819) 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, 846 + ... + 875.

It is an arithmetic number, because the mean of its divisors is an integer number (5166).

2²⁵⁸¹⁵ is an apocalyptic number.

25815 is a deficient number, since it is larger than the sum of its proper divisors (15513).

25815 is a wasteful number, since it uses less digits than its factorization.

25815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1729.

The product of its digits is 400, while the sum is 21.

The square root of 25815 is about 160.6704702178. The cubic root of 25815 is about 29.5545290398.

The spelling of 25815 in words is "twenty-five thousand, eight hundred fifteen".