251231240 has 64 divisors (see below), whose sum is σ = 617924160. Its totient is φ = 91365120.

The previous prime is 251231237. The next prime is 251231311. The reversal of 251231240 is 42132152.

It is a Harshad number since it is a multiple of its sum of digits (20).

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, 31235 + ... + 38445.

It is an arithmetic number, because the mean of its divisors is an integer number (9655065).

Almost surely, 2^251231240 is an apocalyptic number.

251231240 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 251231240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (308962080).

251231240 is an abundant number, since it is smaller than the sum of its proper divisors (366692920).

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

251231240 is a wasteful number, since it uses less digits than its factorization.

251231240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7302 (or 7298 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 251231240 is about 15850.2757073812. The cubic root of 251231240 is about 630.9930086133.

Adding to 251231240 its reverse (42132152), we get a palindrome (293363392).

The spelling of 251231240 in words is "two hundred fifty-one million, two hundred thirty-one thousand, two hundred forty".