25563581 has 2 divisors, whose sum is σ = 25563582. Its totient is φ = 25563580.

The previous prime is 25563553. The next prime is 25563589. The reversal of 25563581 is 18536552.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25452025 + 111556 = 5045^2 + 334^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25563581 is a prime.

It is a super-2 number, since 2×25563581² = 1306993347087122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25563589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12781790 + 12781791.

It is an arithmetic number, because the mean of its divisors is an integer number (12781791).

Almost surely, 2^25563581 is an apocalyptic number.

It is an amenable number.

25563581 is a deficient number, since it is larger than the sum of its proper divisors (1).

25563581 is an equidigital number, since it uses as much as digits as its factorization.

25563581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36000, while the sum is 35.

The square root of 25563581 is about 5056.0440069287. The cubic root of 25563581 is about 294.5826944568.

It can be divided in two parts, 255 and 63581, that added together give a palindrome (63836).

The spelling of 25563581 in words is "twenty-five million, five hundred sixty-three thousand, five hundred eighty-one".