1251391680 has 1008 divisors, whose sum is σ = 5902391040. Its totient is φ = 246343680.

The previous prime is 1251391657. The next prime is 1251391681. The reversal of 1251391680 is 861931521.

It is a tau number, because it is divible by the number of its divisors (1008).

It is a super-2 number, since 2×1251391680² = 3131962273546444800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251391681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 65862711 + ... + 65862729.

Almost surely, 2^1251391680 is an apocalyptic number.

1251391680 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 1251391680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2951195520).

1251391680 is an abundant number, since it is smaller than the sum of its proper divisors (4650999360).

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

1251391680 is a wasteful number, since it uses less digits than its factorization.

1251391680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80 (or 47 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 1251391680 is about 35375.0149116576. The cubic root of 1251391680 is about 1077.6169679026.

The spelling of 1251391680 in words is "one billion, two hundred fifty-one million, three hundred ninety-one thousand, six hundred eighty".