25861921 has 4 divisors (see below), whose sum is σ = 26033344. Its totient is φ = 25690500.

The previous prime is 25861909. The next prime is 25861931. The reversal of 25861921 is 12916852.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 25861921 - 2¹⁷ = 25730849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25861931) 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, 85485 + ... + 85786.

It is an arithmetic number, because the mean of its divisors is an integer number (6508336).

Almost surely, 2^25861921 is an apocalyptic number.

It is an amenable number.

25861921 is a deficient number, since it is larger than the sum of its proper divisors (171423).

25861921 is a wasteful number, since it uses less digits than its factorization.

25861921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171422.

The product of its digits is 8640, while the sum is 34.

The square root of 25861921 is about 5085.4617292828. The cubic root of 25861921 is about 295.7242417486.

The spelling of 25861921 in words is "twenty-five million, eight hundred sixty-one thousand, nine hundred twenty-one".