2565225661 has 2 divisors, whose sum is σ = 2565225662. Its totient is φ = 2565225660.

The previous prime is 2565225647. The next prime is 2565225671. The reversal of 2565225661 is 1665225652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2442237561 + 122988100 = 49419^2 + 11090^2 .

It is a cyclic number.

It is not a de Polignac number, because 2565225661 - 2¹⁵ = 2565192893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2565225601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1282612830 + 1282612831.

It is an arithmetic number, because the mean of its divisors is an integer number (1282612831).

Almost surely, 2^2565225661 is an apocalyptic number.

It is an amenable number.

2565225661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2565225661 is an equidigital number, since it uses as much as digits as its factorization.

2565225661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 216000, while the sum is 40.

The square root of 2565225661 is about 50648.0568334067. The cubic root of 2565225661 is about 1368.9109324866.

Subtracting from 2565225661 its reverse (1665225652), we obtain a palindrome (900000009).

The spelling of 2565225661 in words is "two billion, five hundred sixty-five million, two hundred twenty-five thousand, six hundred sixty-one".