251798989 has 4 divisors (see below), whose sum is σ = 271168156. Its totient is φ = 232429824.

The previous prime is 251798971. The next prime is 251799007. The reversal of 251798989 is 989897152.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (251798971) and next prime (251799007).

It can be written as a sum of positive squares in 2 ways, for example, as 61496964 + 190302025 = 7842^2 + 13795^2 .

It is a cyclic number.

It is not a de Polignac number, because 251798989 - 2⁷ = 251798861 is a prime.

It is a super-2 number, since 2×251798989² = 126805461722844242, 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 (251798189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9684564 + ... + 9684589.

It is an arithmetic number, because the mean of its divisors is an integer number (67792039).

Almost surely, 2^251798989 is an apocalyptic number.

It is an amenable number.

251798989 is a deficient number, since it is larger than the sum of its proper divisors (19369167).

251798989 is a wasteful number, since it uses less digits than its factorization.

251798989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19369166.

The product of its digits is 3265920, while the sum is 58.

The square root of 251798989 is about 15868.1753519426. The cubic root of 251798989 is about 631.4679709436.

The spelling of 251798989 in words is "two hundred fifty-one million, seven hundred ninety-eight thousand, nine hundred eighty-nine".