251955840 has 128 divisors (see below), whose sum is σ = 807693120. Its totient is φ = 66805760.

The previous prime is 251955839. The next prime is 251955853. The reversal of 251955840 is 48559152.

It is a tau number, because it is divible by the number of its divisors (128).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 539287 + ... + 539753.

Almost surely, 2^251955840 is an apocalyptic number.

251955840 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 251955840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (403846560).

251955840 is an abundant number, since it is smaller than the sum of its proper divisors (555737280).

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

251955840 is a wasteful number, since it uses less digits than its factorization.

251955840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 770 (or 758 counting only the distinct ones).

The product of its (nonzero) digits is 72000, while the sum is 39.

The square root of 251955840 is about 15873.1168961865. The cubic root of 251955840 is about 631.5990620494.

The spelling of 251955840 in words is "two hundred fifty-one million, nine hundred fifty-five thousand, eight hundred forty".