1256991120 has 720 divisors, whose sum is σ = 5557144320. Its totient is φ = 251596800.

The previous prime is 1256991119. The next prime is 1256991173. The reversal of 1256991120 is 211996521.

1256991120 is a `hidden beast` number, since 1 + 2 + 569 + 91 + 1 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

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

It is a congruent number.

It is an unprimeable number.

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, 15911241 + ... + 15911319.

It is an arithmetic number, because the mean of its divisors is an integer number (7718256).

Almost surely, 2^1256991120 is an apocalyptic number.

1256991120 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 1256991120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2778572160).

1256991120 is an abundant number, since it is smaller than the sum of its proper divisors (4300153200).

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

1256991120 is a wasteful number, since it uses less digits than its factorization.

1256991120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164 (or 148 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 36.

The square root of 1256991120 is about 35454.0705702462. The cubic root of 1256991120 is about 1079.2218674791.

The spelling of 1256991120 in words is "one billion, two hundred fifty-six million, nine hundred ninety-one thousand, one hundred twenty".