1251511440 has 160 divisors (see below), whose sum is σ = 4139735040. Its totient is φ = 311672832.

The previous prime is 1251511427. The next prime is 1251511453. The reversal of 1251511440 is 441151521.

It is an interprime number because it is at equal distance from previous prime (1251511427) and next prime (1251511453).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 1251511440.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 557841 + ... + 560079.

It is an arithmetic number, because the mean of its divisors is an integer number (25873344).

Almost surely, 2^1251511440 is an apocalyptic number.

1251511440 is a gapful number since it is divisible by the number (10) 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 1251511440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2069867520).

1251511440 is an abundant number, since it is smaller than the sum of its proper divisors (2888223600).

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

1251511440 is a wasteful number, since it uses less digits than its factorization.

1251511440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2409 (or 2403 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 24.

The square root of 1251511440 is about 35376.7075912952. The cubic root of 1251511440 is about 1077.6513433087.

Adding to 1251511440 its reverse (441151521), we get a palindrome (1692662961).

The spelling of 1251511440 in words is "one billion, two hundred fifty-one million, five hundred eleven thousand, four hundred forty".