1251540640 has 192 divisors, whose sum is σ = 3597834240. Its totient is φ = 401863680.

The previous prime is 1251540623. The next prime is 1251540707. The reversal of 1251540640 is 460451521.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 1251540599 and 1251540608.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2191555 + ... + 2192125.

It is an arithmetic number, because the mean of its divisors is an integer number (18738720).

Almost surely, 2^1251540640 is an apocalyptic number.

1251540640 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 1251540640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1798917120).

1251540640 is an abundant number, since it is smaller than the sum of its proper divisors (2346293600).

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

1251540640 is a wasteful number, since it uses less digits than its factorization.

1251540640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 715 (or 707 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 1251540640 is about 35377.1202898144. The cubic root of 1251540640 is about 1077.6597244212.

The spelling of 1251540640 in words is "one billion, two hundred fifty-one million, five hundred forty thousand, six hundred forty".