25665051665 has 24 divisors (see below), whose sum is σ = 34767375720. Its totient is φ = 18161003520.

The previous prime is 25665051647. The next prime is 25665051679. The reversal of 25665051665 is 56615056652.

It can be written as a sum of positive squares in 4 ways, for example, as 2608451329 + 23056600336 = 51073^2 + 151844^2 .

It is not a de Polignac number, because 25665051665 - 2²² = 25660857361 is a prime.

It is a Smith number, since the sum of its digits (47) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 550880 + ... + 595649.

It is an arithmetic number, because the mean of its divisors is an integer number (1448640655).

Almost surely, 2^25665051665 is an apocalyptic number.

It is an amenable number.

25665051665 is a deficient number, since it is larger than the sum of its proper divisors (9102324055).

25665051665 is a wasteful number, since it uses less digits than its factorization.

25665051665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1146593 (or 1146582 counting only the distinct ones).

The product of its (nonzero) digits is 1620000, while the sum is 47.

The spelling of 25665051665 in words is "twenty-five billion, six hundred sixty-five million, fifty-one thousand, six hundred sixty-five".