25646976581 has 2 divisors, whose sum is σ = 25646976582. Its totient is φ = 25646976580.

The previous prime is 25646976541. The next prime is 25646976583. The reversal of 25646976581 is 18567964652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 24515730625 + 1131245956 = 156575^2 + 33634^2 .

It is a cyclic number.

It is not a de Polignac number, because 25646976581 - 2¹⁴ = 25646960197 is a prime.

It is a super-2 number, since 2×25646976581² (a number of 22 digits) contains 22 as substring.

Together with 25646976583, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 25646976581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25646976583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12823488290 + 12823488291.

It is an arithmetic number, because the mean of its divisors is an integer number (12823488291).

Almost surely, 2^25646976581 is an apocalyptic number.

It is an amenable number.

25646976581 is a deficient number, since it is larger than the sum of its proper divisors (1).

25646976581 is an equidigital number, since it uses as much as digits as its factorization.

25646976581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21772800, while the sum is 59.

The spelling of 25646976581 in words is "twenty-five billion, six hundred forty-six million, nine hundred seventy-six thousand, five hundred eighty-one".