1191171596921 has 2 divisors, whose sum is σ = 1191171596922. Its totient is φ = 1191171596920.

The previous prime is 1191171596899. The next prime is 1191171596929. The reversal of 1191171596921 is 1296951711911.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 970154081296 + 221017515625 = 984964^2 + 470125^2 .

It is a cyclic number.

It is not a de Polignac number, because 1191171596921 - 2³⁴ = 1173991727737 is a prime.

It is a super-2 number, since 2×1191171596921² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1191171596929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 595585798460 + 595585798461.

It is an arithmetic number, because the mean of its divisors is an integer number (595585798461).

Almost surely, 2^{1191171596921} is an apocalyptic number.

It is an amenable number.

1191171596921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1191171596921 is an equidigital number, since it uses as much as digits as its factorization.

1191171596921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 306180, while the sum is 53.

The spelling of 1191171596921 in words is "one trillion, one hundred ninety-one billion, one hundred seventy-one million, five hundred ninety-six thousand, nine hundred twenty-one".