1999121256 has 256 divisors, whose sum is σ = 6569164800. Its totient is φ = 556416000.

The previous prime is 1999121203. The next prime is 1999121263. The reversal of 1999121256 is 6521219991.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1736281 + ... + 1737431.

It is an arithmetic number, because the mean of its divisors is an integer number (25660800).

Almost surely, 2^1999121256 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1999121256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3284582400).

1999121256 is an abundant number, since it is smaller than the sum of its proper divisors (4570043544).

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

1999121256 is a wasteful number, since it uses less digits than its factorization.

1999121256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1237 (or 1227 counting only the distinct ones).

The product of its digits is 87480, while the sum is 45.

The square root of 1999121256 is about 44711.5338139948. The cubic root of 1999121256 is about 1259.7364981861.

The spelling of 1999121256 in words is "one billion, nine hundred ninety-nine million, one hundred twenty-one thousand, two hundred fifty-six".