251642280 has 128 divisors (see below), whose sum is σ = 787449600. Its totient is φ = 64253952.

The previous prime is 251642273. The next prime is 251642311. The reversal of 251642280 is 82246152.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 580944 + ... + 581376.

It is an arithmetic number, because the mean of its divisors is an integer number (6151950).

Almost surely, 2^251642280 is an apocalyptic number.

251642280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 251642280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (393724800).

251642280 is an abundant number, since it is smaller than the sum of its proper divisors (535807320).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

251642280 is a wasteful number, since it uses less digits than its factorization.

251642280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 643 (or 639 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 30.

The square root of 251642280 is about 15863.2367441200. The cubic root of 251642280 is about 631.3369441398.

The spelling of 251642280 in words is "two hundred fifty-one million, six hundred forty-two thousand, two hundred eighty".