25645661 has 4 divisors (see below), whose sum is σ = 25894752. Its totient is φ = 25396572.

The previous prime is 25645651. The next prime is 25645663. The reversal of 25645661 is 16654652.

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 25645661 - 2¹⁴ = 25629277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25645663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 124391 + ... + 124596.

It is an arithmetic number, because the mean of its divisors is an integer number (6473688).

Almost surely, 2^25645661 is an apocalyptic number.

It is an amenable number.

25645661 is a deficient number, since it is larger than the sum of its proper divisors (249091).

25645661 is a wasteful number, since it uses less digits than its factorization.

25645661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 249090.

The product of its digits is 43200, while the sum is 35.

The square root of 25645661 is about 5064.1545197594. The cubic root of 25645661 is about 294.8976414007.

The spelling of 25645661 in words is "twenty-five million, six hundred forty-five thousand, six hundred sixty-one".