1991663896 has 16 divisors (see below), whose sum is σ = 3735473040. Its totient is φ = 995537760.

The previous prime is 1991663881. The next prime is 1991663897. The reversal of 1991663896 is 6983661991.

It is a self number, because there is not a number n which added to its sum of digits gives 1991663896.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991663897) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6540 + ... + 63451.

It is an arithmetic number, because the mean of its divisors is an integer number (233467065).

Almost surely, 2^1991663896 is an apocalyptic number.

It is an amenable number.

1991663896 is a deficient number, since it is larger than the sum of its proper divisors (1743809144).

1991663896 is a wasteful number, since it uses less digits than its factorization.

1991663896 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73554 (or 73550 counting only the distinct ones).

The product of its digits is 3779136, while the sum is 58.

The square root of 1991663896 is about 44628.0617549093. The cubic root of 1991663896 is about 1258.1681400774.

The spelling of 1991663896 in words is "one billion, nine hundred ninety-one million, six hundred sixty-three thousand, eight hundred ninety-six".