251989920 has 384 divisors, whose sum is σ = 1087188480. Its totient is φ = 53084160.

The previous prime is 251989891. The next prime is 251989937. The reversal of 251989920 is 29989152.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a zygodrome in base 4.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 392800 + ... + 393440.

It is an arithmetic number, because the mean of its divisors is an integer number (2831220).

Almost surely, 2^251989920 is an apocalyptic number.

251989920 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 251989920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (543594240).

251989920 is an abundant number, since it is smaller than the sum of its proper divisors (835198560).

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

251989920 is a wasteful number, since it uses less digits than its factorization.

251989920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 685 (or 671 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 45.

The square root of 251989920 is about 15874.1903730553. The cubic root of 251989920 is about 631.6275378405.

The spelling of 251989920 in words is "two hundred fifty-one million, nine hundred eighty-nine thousand, nine hundred twenty".