1251440640 has 288 divisors, whose sum is σ = 4466629440. Its totient is φ = 323813376.

The previous prime is 1251440629. The next prime is 1251440647. The reversal of 1251440640 is 460441521.

1251440640 is a `hidden beast` number, since 1 + 2 + 5 + 14 + 4 + 0 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a super-2 number, since 2×1251440640² = 3132207350887219200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251440647) 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, 3409737 + ... + 3410103.

It is an arithmetic number, because the mean of its divisors is an integer number (15509130).

Almost surely, 2^1251440640 is an apocalyptic number.

1251440640 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 1251440640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2233314720).

1251440640 is an abundant number, since it is smaller than the sum of its proper divisors (3215188800).

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

1251440640 is a wasteful number, since it uses less digits than its factorization.

1251440640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 437 (or 414 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 1251440640 is about 35375.7069187317. The cubic root of 1251440640 is about 1077.6310214399.

The spelling of 1251440640 in words is "one billion, two hundred fifty-one million, four hundred forty thousand, six hundred forty".