25665840857 has 2 divisors, whose sum is σ = 25665840858. Its totient is φ = 25665840856.

The previous prime is 25665840847. The next prime is 25665840877. The reversal of 25665840857 is 75804856652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19947607696 + 5718233161 = 141236^2 + 75619^2 .

It is a cyclic number.

It is not a de Polignac number, because 25665840857 - 2⁴ = 25665840841 is a prime.

It is not a weakly prime, because it can be changed into another prime (25665840847) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12832920428 + 12832920429.

It is an arithmetic number, because the mean of its divisors is an integer number (12832920429).

Almost surely, 2^25665840857 is an apocalyptic number.

It is an amenable number.

25665840857 is a deficient number, since it is larger than the sum of its proper divisors (1).

25665840857 is an equidigital number, since it uses as much as digits as its factorization.

25665840857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128000, while the sum is 56.

The spelling of 25665840857 in words is "twenty-five billion, six hundred sixty-five million, eight hundred forty thousand, eight hundred fifty-seven".