25591921 has 4 divisors (see below), whose sum is σ = 25658100. Its totient is φ = 25525744.

The previous prime is 25591889. The next prime is 25591931. The reversal of 25591921 is 12919552.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10653696 + 14938225 = 3264^2 + 3865^2 .

It is a cyclic number.

It is not a de Polignac number, because 25591921 - 2⁵ = 25591889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25591931) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32506 + ... + 33283.

It is an arithmetic number, because the mean of its divisors is an integer number (6414525).

Almost surely, 2^25591921 is an apocalyptic number.

It is an amenable number.

25591921 is a deficient number, since it is larger than the sum of its proper divisors (66179).

25591921 is an equidigital number, since it uses as much as digits as its factorization.

25591921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66178.

The product of its digits is 8100, while the sum is 34.

The square root of 25591921 is about 5058.8458169824. The cubic root of 25591921 is about 294.6915132017.

The spelling of 25591921 in words is "twenty-five million, five hundred ninety-one thousand, nine hundred twenty-one".