25811989 has 4 divisors (see below), whose sum is σ = 29499424. Its totient is φ = 22124556.

The previous prime is 25811987. The next prime is 25811993. The reversal of 25811989 is 98911852.

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 25811989 - 2¹ = 25811987 is a prime.

It is a super-2 number, since 2×25811989² = 1332517552272242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25811987) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1843707 + ... + 1843720.

It is an arithmetic number, because the mean of its divisors is an integer number (7374856).

Almost surely, 2^25811989 is an apocalyptic number.

It is an amenable number.

25811989 is a deficient number, since it is larger than the sum of its proper divisors (3687435).

25811989 is an equidigital number, since it uses as much as digits as its factorization.

25811989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3687434.

The product of its digits is 51840, while the sum is 43.

The square root of 25811989 is about 5080.5500686441. The cubic root of 25811989 is about 295.5337993849.

The spelling of 25811989 in words is "twenty-five million, eight hundred eleven thousand, nine hundred eighty-nine".