1991311340555 has 16 divisors (see below), whose sum is σ = 2483688247200. Its totient is φ = 1530826671360.

The previous prime is 1991311340527. The next prime is 1991311340561. The reversal of 1991311340555 is 5550431131991.

It is not a de Polignac number, because 1991311340555 - 2³⁰ = 1990237598731 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32512490 + ... + 32573679.

It is an arithmetic number, because the mean of its divisors is an integer number (155230515450).

Almost surely, 2^{1991311340555} is an apocalyptic number.

1991311340555 is a deficient number, since it is larger than the sum of its proper divisors (492376906645).

1991311340555 is a wasteful number, since it uses less digits than its factorization.

1991311340555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65086414.

The product of its (nonzero) digits is 364500, while the sum is 47.

The spelling of 1991311340555 in words is "one trillion, nine hundred ninety-one billion, three hundred eleven million, three hundred forty thousand, five hundred fifty-five".