25905868209 has 27 divisors (see below), whose sum is σ = 40529255403. Its totient is φ = 15938209872.

The previous prime is 25905868201. The next prime is 25905868213. The reversal of 25905868209 is 90286850952.

The square root of 25905868209 is 160953.

It is a perfect power (a square), and thus also a powerful number.

25905868209 is a `hidden beast` number, since 2 + 59 + 0 + 586 + 8 + 2 + 0 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 3832229025 + 22073639184 = 61905^2 + 148572^2 .

It is not a de Polignac number, because 25905868209 - 2³ = 25905868201 is a prime.

It is a super-2 number, since 2×25905868209² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (25905868201) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 6275104 + ... + 6279230.

Almost surely, 2^25905868209 is an apocalyptic number.

25905868209 is the 160953-rd square number.

25905868209 is the 80477-th centered octagonal number.

It is an amenable number.

25905868209 is a deficient number, since it is larger than the sum of its proper divisors (14623387194).

25905868209 is an frugal number, since it uses more digits than its factorization.

25905868209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8286 (or 4143 counting only the distinct ones).

The product of its (nonzero) digits is 3110400, while the sum is 54.

The spelling of 25905868209 in words is "twenty-five billion, nine hundred five million, eight hundred sixty-eight thousand, two hundred nine".