1991863328 has 288 divisors, whose sum is σ = 5349153600. Its totient is φ = 721115136.

The previous prime is 1991863303. The next prime is 1991863333. The reversal of 1991863328 is 8233681991.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 14329883 + ... + 14330021.

It is an arithmetic number, because the mean of its divisors is an integer number (18573450).

Almost surely, 2^1991863328 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 1991863328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2674576800).

1991863328 is an abundant number, since it is smaller than the sum of its proper divisors (3357290272).

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

1991863328 is a wasteful number, since it uses less digits than its factorization.

1991863328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232 (or 217 counting only the distinct ones).

The product of its digits is 559872, while the sum is 50.

The square root of 1991863328 is about 44630.2960778886. The cubic root of 1991863328 is about 1258.2101335440.

The spelling of 1991863328 in words is "one billion, nine hundred ninety-one million, eight hundred sixty-three thousand, three hundred twenty-eight".