251540240 has 160 divisors (see below), whose sum is σ = 719953920. Its totient is φ = 79805952.

The previous prime is 251540227. The next prime is 251540249. The reversal of 251540240 is 42045152.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (251540249) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 499829 + ... + 500331.

It is an arithmetic number, because the mean of its divisors is an integer number (4499712).

Almost surely, 2^251540240 is an apocalyptic number.

251540240 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 251540240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (359976960).

251540240 is an abundant number, since it is smaller than the sum of its proper divisors (468413680).

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

251540240 is a wasteful number, since it uses less digits than its factorization.

251540240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 589 (or 583 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 23.

The square root of 251540240 is about 15860.0201765319. The cubic root of 251540240 is about 631.2515976825.

Adding to 251540240 its reverse (42045152), we get a palindrome (293585392).

It can be divided in two parts, 2515 and 40240, that multiplied together give a square (101203600 = 10060²).

The spelling of 251540240 in words is "two hundred fifty-one million, five hundred forty thousand, two hundred forty".