25561181 has 4 divisors (see below), whose sum is σ = 25814364. Its totient is φ = 25308000.

The previous prime is 25561147. The next prime is 25561189. The reversal of 25561181 is 18116552.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12355225 + 13205956 = 3515^2 + 3634^2 .

It is a cyclic number.

It is not a de Polignac number, because 25561181 - 2¹⁸ = 25299037 is a prime.

It is a super-2 number, since 2×25561181² = 1306747948229522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25561189) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 126440 + ... + 126641.

It is an arithmetic number, because the mean of its divisors is an integer number (6453591).

Almost surely, 2^25561181 is an apocalyptic number.

It is an amenable number.

25561181 is a deficient number, since it is larger than the sum of its proper divisors (253183).

25561181 is a wasteful number, since it uses less digits than its factorization.

25561181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 253182.

The product of its digits is 2400, while the sum is 29.

The square root of 25561181 is about 5055.8066616515. The cubic root of 25561181 is about 294.5734753442.

The spelling of 25561181 in words is "twenty-five million, five hundred sixty-one thousand, one hundred eighty-one".