25218109 has 4 divisors (see below), whose sum is σ = 28820704. Its totient is φ = 21615516.

The previous prime is 25218103. The next prime is 25218113. The reversal of 25218109 is 90181252.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 25218109 - 2⁵ = 25218077 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25218103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1801287 + ... + 1801300.

It is an arithmetic number, because the mean of its divisors is an integer number (7205176).

Almost surely, 2^25218109 is an apocalyptic number.

It is an amenable number.

25218109 is a deficient number, since it is larger than the sum of its proper divisors (3602595).

25218109 is an equidigital number, since it uses as much as digits as its factorization.

25218109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3602594.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 25218109 is about 5021.7635348551. The cubic root of 25218109 is about 293.2496522951.

The spelling of 25218109 in words is "twenty-five million, two hundred eighteen thousand, one hundred nine".