25665621 has 16 divisors (see below), whose sum is σ = 35130240. Its totient is φ = 16660800.

The previous prime is 25665617. The next prime is 25665641. The reversal of 25665621 is 12656652.

It is a happy number.

It is not a de Polignac number, because 25665621 - 2² = 25665617 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25665641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23475 + ... + 24543.

It is an arithmetic number, because the mean of its divisors is an integer number (2195640).

Almost surely, 2^25665621 is an apocalyptic number.

It is an amenable number.

25665621 is a deficient number, since it is larger than the sum of its proper divisors (9464619).

25665621 is a wasteful number, since it uses less digits than its factorization.

25665621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1276.

The product of its digits is 21600, while the sum is 33.

The square root of 25665621 is about 5066.1248504157. The cubic root of 25665621 is about 294.9741277703.

The spelling of 25665621 in words is "twenty-five million, six hundred sixty-five thousand, six hundred twenty-one".