1991992991992 has 32 divisors (see below), whose sum is σ = 3748572600480. Its totient is φ = 992374190080.

The previous prime is 1991992991983. The next prime is 1991992992047. The reversal of 1991992991992 is 2991992991991.

It is a super-2 number, since 2×1991992991992² (a number of 25 digits) contains 22 as substring.

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, 37791768 + ... + 37844440.

It is an arithmetic number, because the mean of its divisors is an integer number (117142893765).

Almost surely, 2^{1991992991992} is an apocalyptic number.

It is an amenable number.

1991992991992 is a deficient number, since it is larger than the sum of its proper divisors (1756579608488).

1991992991992 is a wasteful number, since it uses less digits than its factorization.

1991992991992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69783 (or 69779 counting only the distinct ones).

The product of its digits is 172186884, while the sum is 79.

Subtracting 1991992991992 from its reverse (2991992991991), we obtain a palindrome (999999999999).

The spelling of 1991992991992 in words is "one trillion, nine hundred ninety-one billion, nine hundred ninety-two million, nine hundred ninety-one thousand, nine hundred ninety-two".