25805721 has 4 divisors (see below), whose sum is σ = 34407632. Its totient is φ = 17203812.

The previous prime is 25805707. The next prime is 25805729. The reversal of 25805721 is 12750852.

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 not a de Polignac number, because 25805721 - 2⁶ = 25805657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25805729) 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, 4300951 + ... + 4300956.

It is an arithmetic number, because the mean of its divisors is an integer number (8601908).

Almost surely, 2^25805721 is an apocalyptic number.

It is an amenable number.

25805721 is a deficient number, since it is larger than the sum of its proper divisors (8601911).

25805721 is an equidigital number, since it uses as much as digits as its factorization.

25805721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8601910.

The product of its (nonzero) digits is 5600, while the sum is 30.

The square root of 25805721 is about 5079.9331688517. The cubic root of 25805721 is about 295.5098756724.

The spelling of 25805721 in words is "twenty-five million, eight hundred five thousand, seven hundred twenty-one".