25921 has 9 divisors (see below), whose sum is σ = 31521. Its totient is φ = 21252.

The previous prime is 25919. The next prime is 25931. The reversal of 25921 is 12952.

25921 = T₁₆₀ + T₁₆₁.

The square root of 25921 is 161.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 25921 - 2¹ = 25919 is a prime.

It is an Ulam number.

Its product of digits (180) is a multiple of the sum of its prime divisors (30).

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (25931) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1116 + ... + 1138.

25921 is a Friedman number, since it can be written as (152+9)^2, using all its digits and the basic arithmetic operations.

2²⁵⁹²¹ is an apocalyptic number.

25921 is the 161-st square number.

25921 is the 81-st centered octagonal number.

It is an amenable number.

25921 is a deficient number, since it is larger than the sum of its proper divisors (5600).

25921 is an equidigital number, since it uses as much as digits as its factorization.

25921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60 (or 30 counting only the distinct ones).

The product of its digits is 180, while the sum is 19.

The cubic root of 25921 is about 29.5949254754.

It can be divided in two parts, 25 and 921, that added together give a triangular number (946 = T₄₃).

The spelling of 25921 in words is "twenty-five thousand, nine hundred twenty-one".