1991099109020 has 24 divisors (see below), whose sum is σ = 4778637861984. Its totient is φ = 682662551616.

The previous prime is 1991099108959. The next prime is 1991099109067. The reversal of 1991099109020 is 209019901991.

It is a self number, because there is not a number n which added to its sum of digits gives 1991099109020.

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, 7111068107 + ... + 7111068386.

It is an arithmetic number, because the mean of its divisors is an integer number (199109910916).

Almost surely, 2^{1991099109020} is an apocalyptic number.

1991099109020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1991099109020 is an abundant number, since it is smaller than the sum of its proper divisors (2787538752964).

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

1991099109020 is a wasteful number, since it uses less digits than its factorization.

1991099109020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14222136509 (or 14222136507 counting only the distinct ones).

The product of its (nonzero) digits is 118098, while the sum is 50.

The spelling of 1991099109020 in words is "one trillion, nine hundred ninety-one billion, ninety-nine million, one hundred nine thousand, twenty".