1991563964802 has 40 divisors (see below), whose sum is σ = 4508584513356. Its totient is φ = 657010787328.

The previous prime is 1991563964791. The next prime is 1991563964851. The reversal of 1991563964802 is 2084693651991.

1991563964802 is a `hidden beast` number, since 1 + 9 + 9 + 1 + 5 + 63 + 96 + 480 + 2 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1773289059201 + 218274905601 = 1331649^2 + 467199^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 1991563964802.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 63353383 + ... + 63384810.

Almost surely, 2^{1991563964802} is an apocalyptic number.

1991563964802 is an abundant number, since it is smaller than the sum of its proper divisors (2517020548554).

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

1991563964802 is a wasteful number, since it uses less digits than its factorization.

1991563964802 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126738304 (or 126738295 counting only the distinct ones).

The product of its (nonzero) digits is 25194240, while the sum is 63.

The spelling of 1991563964802 in words is "one trillion, nine hundred ninety-one billion, five hundred sixty-three million, nine hundred sixty-four thousand, eight hundred two".