25661988 has 48 divisors (see below), whose sum is σ = 72582720. Its totient is φ = 7776000.

The previous prime is 25661981. The next prime is 25662037. The reversal of 25661988 is 88916652.

25661988 is a `hidden beast` number, since 2 + 566 + 1 + 9 + 88 = 666.

It is a super-2 number, since 2×25661988² = 1317075256224288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (25661981) 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, 9613 + ... + 11988.

It is an arithmetic number, because the mean of its divisors is an integer number (1512140).

Almost surely, 2^25661988 is an apocalyptic number.

It is an amenable number.

25661988 is an abundant number, since it is smaller than the sum of its proper divisors (46920732).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

25661988 is a wasteful number, since it uses less digits than its factorization.

25661988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21625 (or 21617 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The square root of 25661988 is about 5065.7662796462. The cubic root of 25661988 is about 294.9602091308.

It can be divided in two parts, 2566 and 1988, that added together give a palindrome (4554).

The spelling of 25661988 in words is "twenty-five million, six hundred sixty-one thousand, nine hundred eighty-eight".