25218581 has 2 divisors, whose sum is σ = 25218582. Its totient is φ = 25218580.

The previous prime is 25218577. The next prime is 25218587. The reversal of 25218581 is 18581252.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24344356 + 874225 = 4934^2 + 935^2 .

It is a cyclic number.

It is not a de Polignac number, because 25218581 - 2² = 25218577 is a prime.

It is a super-2 number, since 2×25218581² = 1271953655307122, which contains 22 as substring.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25218587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12609290 + 12609291.

It is an arithmetic number, because the mean of its divisors is an integer number (12609291).

Almost surely, 2^25218581 is an apocalyptic number.

It is an amenable number.

25218581 is a deficient number, since it is larger than the sum of its proper divisors (1).

25218581 is an equidigital number, since it uses as much as digits as its factorization.

25218581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6400, while the sum is 32.

The square root of 25218581 is about 5021.8105300778. The cubic root of 25218581 is about 293.2514818398.

The spelling of 25218581 in words is "twenty-five million, two hundred eighteen thousand, five hundred eighty-one".