25564646557 has 2 divisors, whose sum is σ = 25564646558. Its totient is φ = 25564646556.

The previous prime is 25564646449. The next prime is 25564646567. The reversal of 25564646557 is 75564646552.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19940546521 + 5624100036 = 141211^2 + 74994^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25564646557 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 25564646498 and 25564646507.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25564646567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12782323278 + 12782323279.

It is an arithmetic number, because the mean of its divisors is an integer number (12782323279).

Almost surely, 2^25564646557 is an apocalyptic number.

It is an amenable number.

25564646557 is a deficient number, since it is larger than the sum of its proper divisors (1).

25564646557 is an equidigital number, since it uses as much as digits as its factorization.

25564646557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240000, while the sum is 55.

It can be divided in two parts, 255646 and 46557, that added together give a palindrome (302203).

The spelling of 25564646557 in words is "twenty-five billion, five hundred sixty-four million, six hundred forty-six thousand, five hundred fifty-seven".