251989 has 4 divisors (see below), whose sum is σ = 256320. Its totient is φ = 247660.

The previous prime is 251983. The next prime is 252001. The reversal of 251989 is 989152.

251989 is nontrivially palindromic in base 15.

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 251989 - 2⁷ = 251861 is a prime.

It is a super-2 number, since 2×251989² = 126996912242, 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 (251983) 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, 2077 + ... + 2194.

It is an arithmetic number, because the mean of its divisors is an integer number (64080).

2²⁵¹⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

251989 is a deficient number, since it is larger than the sum of its proper divisors (4331).

251989 is an equidigital number, since it uses as much as digits as its factorization.

251989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4330.

The product of its digits is 6480, while the sum is 34.

The square root of 251989 is about 501.9850595386. The cubic root of 251989 is about 63.1626769162.

The spelling of 251989 in words is "two hundred fifty-one thousand, nine hundred eighty-nine".