251515920 has 120 divisors (see below), whose sum is σ = 823179456. Its totient is φ = 63518976.

The previous prime is 251515919. The next prime is 251515921. The reversal of 251515920 is 29515152.

It is an interprime number because it is at equal distance from previous prime (251515919) and next prime (251515921).

It is a tau number, because it is divible by the number of its divisors (120).

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

It is not an unprimeable number, because it can be changed into a prime (251515921) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 85189 + ... + 88091.

Almost surely, 2^251515920 is an apocalyptic number.

251515920 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 251515920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (411589728).

251515920 is an abundant number, since it is smaller than the sum of its proper divisors (571663536).

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

251515920 is a wasteful number, since it uses less digits than its factorization.

251515920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2957 (or 2932 counting only the distinct ones).

The product of its (nonzero) digits is 4500, while the sum is 30.

The square root of 251515920 is about 15859.2534502731. The cubic root of 251515920 is about 631.2312529805.

The spelling of 251515920 in words is "two hundred fifty-one million, five hundred fifteen thousand, nine hundred twenty".