25644003661 has 4 divisors (see below), whose sum is σ = 25686251392. Its totient is φ = 25601755932.

The previous prime is 25644003607. The next prime is 25644003667. The reversal of 25644003661 is 16630044652.

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 25644003661 - 2⁹ = 25644003149 is a prime.

It is a super-2 number, since 2×25644003661² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 25644003661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25644003667) 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, 21122955 + ... + 21124168.

It is an arithmetic number, because the mean of its divisors is an integer number (6421562848).

Almost surely, 2^25644003661 is an apocalyptic number.

It is an amenable number.

25644003661 is a deficient number, since it is larger than the sum of its proper divisors (42247731).

25644003661 is an equidigital number, since it uses as much as digits as its factorization.

25644003661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42247730.

The product of its (nonzero) digits is 103680, while the sum is 37.

The spelling of 25644003661 in words is "twenty-five billion, six hundred forty-four million, three thousand, six hundred sixty-one".