161600665101991 has 2 divisors, whose sum is σ = 161600665101992. Its totient is φ = 161600665101990.

The previous prime is 161600665101983. The next prime is 161600665102021. The reversal of 161600665101991 is 199101566006161.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 161600665101991 - 2³ = 161600665101983 is a prime.

It is a super-2 number, since 2×161600665101991² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161600665101961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80800332550995 + 80800332550996.

It is an arithmetic number, because the mean of its divisors is an integer number (80800332550996).

Almost surely, 2^{161600665101991} is an apocalyptic number.

161600665101991 is a deficient number, since it is larger than the sum of its proper divisors (1).

161600665101991 is an equidigital number, since it uses as much as digits as its factorization.

161600665101991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 524880, while the sum is 52.

The spelling of 161600665101991 in words is "one hundred sixty-one trillion, six hundred billion, six hundred sixty-five million, one hundred one thousand, nine hundred ninety-one".