25991217 has 18 divisors (see below), whose sum is σ = 43673058. Its totient is φ = 14851872.

The previous prime is 25991213. The next prime is 25991227. The reversal of 25991217 is 71219952.

It can be written as a sum of positive squares in only one way, i.e., 14130081 + 11861136 = 3759^2 + 3444^2 .

It is not a de Polignac number, because 25991217 - 2² = 25991213 is a prime.

It is a super-2 number, since 2×25991217² = 1351086722282178, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (25991213) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 29028 + ... + 29909.

It is an arithmetic number, because the mean of its divisors is an integer number (2426281).

Almost surely, 2^25991217 is an apocalyptic number.

It is an amenable number.

25991217 is a deficient number, since it is larger than the sum of its proper divisors (17681841).

25991217 is a wasteful number, since it uses less digits than its factorization.

25991217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58957 (or 58947 counting only the distinct ones).

The product of its digits is 11340, while the sum is 36.

The square root of 25991217 is about 5098.1581968393. The cubic root of 25991217 is about 296.2162446184.

The spelling of 25991217 in words is "twenty-five million, nine hundred ninety-one thousand, two hundred seventeen".