1991919520885 has 8 divisors (see below), whose sum is σ = 2731775342976. Its totient is φ = 1365887671440.

The previous prime is 1991919520819. The next prime is 1991919520933. The reversal of 1991919520885 is 5880259191991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1991919520885 - 2³¹ = 1989772037237 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1991919520885.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28455993121 + ... + 28455993190.

It is an arithmetic number, because the mean of its divisors is an integer number (341471917872).

Almost surely, 2^{1991919520885} is an apocalyptic number.

It is an amenable number.

1991919520885 is a deficient number, since it is larger than the sum of its proper divisors (739855822091).

1991919520885 is an equidigital number, since it uses as much as digits as its factorization.

1991919520885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56911986323.

The product of its (nonzero) digits is 20995200, while the sum is 67.

The spelling of 1991919520885 in words is "one trillion, nine hundred ninety-one billion, nine hundred nineteen million, five hundred twenty thousand, eight hundred eighty-five".