25638721 has 8 divisors (see below), whose sum is σ = 26855424. Its totient is φ = 24430560.

The previous prime is 25638713. The next prime is 25638751. The reversal of 25638721 is 12783652.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 25638721 - 2³ = 25638713 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25638751) 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, 4480 + ... + 8446.

It is an arithmetic number, because the mean of its divisors is an integer number (3356928).

Almost surely, 2^25638721 is an apocalyptic number.

It is an amenable number.

25638721 is a deficient number, since it is larger than the sum of its proper divisors (1216703).

25638721 is a wasteful number, since it uses less digits than its factorization.

25638721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4271.

The product of its digits is 20160, while the sum is 34.

The square root of 25638721 is about 5063.4692652370. The cubic root of 25638721 is about 294.8710381445.

The spelling of 25638721 in words is "twenty-five million, six hundred thirty-eight thousand, seven hundred twenty-one".