2991780871991 has 16 divisors (see below), whose sum is σ = 3129606014976. Its totient is φ = 2854607000256.

The previous prime is 2991780871967. The next prime is 2991780872029. The reversal of 2991780871991 is 1991780871992.

2991780871991 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 2991780871991 - 2²⁶ = 2991713763127 is a prime.

It is a super-2 number, since 2×2991780871991² (a number of 26 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2991780871091) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23804171 + ... + 23929523.

It is an arithmetic number, because the mean of its divisors is an integer number (195600375936).

Almost surely, 2^{2991780871991} is an apocalyptic number.

2991780871991 is a deficient number, since it is larger than the sum of its proper divisors (137825142985).

2991780871991 is a wasteful number, since it uses less digits than its factorization.

2991780871991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127942.

The product of its (nonzero) digits is 41150592, while the sum is 71.

Subtracting from 2991780871991 its reverse (1991780871992), we obtain a palindrome (999999999999).

The spelling of 2991780871991 in words is "two trillion, nine hundred ninety-one billion, seven hundred eighty million, eight hundred seventy-one thousand, nine hundred ninety-one".