25521661 has 16 divisors (see below), whose sum is σ = 28892160. Its totient is φ = 22342320.

The previous prime is 25521647. The next prime is 25521667. The reversal of 25521661 is 16612552.

It is not a de Polignac number, because 25521661 - 2⁹ = 25521149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25521667) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 37026 + ... + 37708.

It is an arithmetic number, because the mean of its divisors is an integer number (1805760).

Almost surely, 2^25521661 is an apocalyptic number.

It is an amenable number.

25521661 is a deficient number, since it is larger than the sum of its proper divisors (3370499).

25521661 is a wasteful number, since it uses less digits than its factorization.

25521661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816.

The product of its digits is 3600, while the sum is 28.

The square root of 25521661 is about 5051.8967725004. The cubic root of 25521661 is about 294.4215842332.

The spelling of 25521661 in words is "twenty-five million, five hundred twenty-one thousand, six hundred sixty-one".