1991127011329 has 27 divisors (see below), whose sum is σ = 2197458672003. Its totient is φ = 1803757683024.

The previous prime is 1991127011317. The next prime is 1991127011351. The reversal of 1991127011329 is 9231107211991.

The square root of 1991127011329 is 1411073.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 598963001329 + 1392164010000 = 773927^2 + 1179900^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1991127011329 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1991127011129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 616637287 + ... + 616640515.

Almost surely, 2^{1991127011329} is an apocalyptic number.

1991127011329 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

1991127011329 is the 1411073-rd square number.

1991127011329 is the 705537-th centered octagonal number.

It is an amenable number.

1991127011329 is a deficient number, since it is larger than the sum of its proper divisors (206331660674).

1991127011329 is an frugal number, since it uses more digits than its factorization.

1991127011329 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6542 (or 3271 counting only the distinct ones).

The product of its (nonzero) digits is 61236, while the sum is 46.

The spelling of 1991127011329 in words is "one trillion, nine hundred ninety-one billion, one hundred twenty-seven million, eleven thousand, three hundred twenty-nine".