1991777795903 has 24 divisors (see below), whose sum is σ = 2487811130784. Its totient is φ = 1584181132800.

The previous prime is 1991777795899. The next prime is 1991777795911. The reversal of 1991777795903 is 3095977771991.

It is a happy number.

It is not a de Polignac number, because 1991777795903 - 2² = 1991777795899 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991777795993) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16779518 + ... + 16897803.

It is an arithmetic number, because the mean of its divisors is an integer number (103658797116).

Almost surely, 2^{1991777795903} is an apocalyptic number.

1991777795903 is a deficient number, since it is larger than the sum of its proper divisors (496033334881).

1991777795903 is a wasteful number, since it uses less digits than its factorization.

1991777795903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33677423 (or 33677416 counting only the distinct ones).

The product of its (nonzero) digits is 236294415, while the sum is 74.

The spelling of 1991777795903 in words is "one trillion, nine hundred ninety-one billion, seven hundred seventy-seven million, seven hundred ninety-five thousand, nine hundred three".