251987998 has 8 divisors (see below), whose sum is σ = 386772408. Its totient is φ = 123063864.

The previous prime is 251987987. The next prime is 251988007. The reversal of 251987998 is 899789152.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×251987998² = 126995902272096008, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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, 1464961 + ... + 1465132.

It is an arithmetic number, because the mean of its divisors is an integer number (48346551).

Almost surely, 2^251987998 is an apocalyptic number.

251987998 is a deficient number, since it is larger than the sum of its proper divisors (134784410).

251987998 is a wasteful number, since it uses less digits than its factorization.

251987998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2930138.

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

The square root of 251987998 is about 15874.1298344193. The cubic root of 251987998 is about 631.6259319678.

The spelling of 251987998 in words is "two hundred fifty-one million, nine hundred eighty-seven thousand, nine hundred ninety-eight".