1991148768 has 144 divisors (see below), whose sum is σ = 6489022176. Its totient is φ = 567336960.

The previous prime is 1991148743. The next prime is 1991148781. The reversal of 1991148768 is 8678411991.

1991148768 is a `hidden beast` number, since 1 + 99 + 11 + 487 + 68 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 871788 + ... + 874068.

It is an arithmetic number, because the mean of its divisors is an integer number (45062654).

Almost surely, 2^1991148768 is an apocalyptic number.

1991148768 is a gapful number since it is divisible by the number (18) 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 1991148768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3244511088).

1991148768 is an abundant number, since it is smaller than the sum of its proper divisors (4497873408).

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

1991148768 is a wasteful number, since it uses less digits than its factorization.

1991148768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2737 (or 2726 counting only the distinct ones).

The product of its digits is 870912, while the sum is 54.

The square root of 1991148768 is about 44622.2900353624. The cubic root of 1991148768 is about 1258.0596590022.

The spelling of 1991148768 in words is "one billion, nine hundred ninety-one million, one hundred forty-eight thousand, seven hundred sixty-eight".