25645311261 has 20 divisors (see below), whose sum is σ = 38589311772. Its totient is φ = 16972072128.

The previous prime is 25645311239. The next prime is 25645311281. The reversal of 25645311261 is 16211354652.

25645311261 is a `hidden beast` number, since 2 + 5 + 64 + 531 + 1 + 2 + 61 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 9507420036 + 16137891225 = 97506^2 + 127035^2 .

It is not a de Polignac number, because 25645311261 - 2⁹ = 25645310749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25645311221) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1144410 + ... + 1166603.

Almost surely, 2^25645311261 is an apocalyptic number.

It is an amenable number.

25645311261 is a deficient number, since it is larger than the sum of its proper divisors (12944000511).

25645311261 is a wasteful number, since it uses less digits than its factorization.

25645311261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2311162 (or 2311153 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The spelling of 25645311261 in words is "twenty-five billion, six hundred forty-five million, three hundred eleven thousand, two hundred sixty-one".