161971764217 has 2 divisors, whose sum is σ = 161971764218. Its totient is φ = 161971764216.

The previous prime is 161971764197. The next prime is 161971764233. The reversal of 161971764217 is 712467179161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155187935721 + 6783828496 = 393939^2 + 82364^2 .

It is a cyclic number.

It is not a de Polignac number, because 161971764217 - 2⁷ = 161971764089 is a prime.

It is a super-3 number, since 3×161971764217³ (a number of 35 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (161971764517) by changing a digit.

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 as a sum of consecutive naturals, namely, 80985882108 + 80985882109.

It is an arithmetic number, because the mean of its divisors is an integer number (80985882109).

Almost surely, 2^161971764217 is an apocalyptic number.

It is an amenable number.

161971764217 is a deficient number, since it is larger than the sum of its proper divisors (1).

161971764217 is an equidigital number, since it uses as much as digits as its factorization.

161971764217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 889056, while the sum is 52.

The spelling of 161971764217 in words is "one hundred sixty-one billion, nine hundred seventy-one million, seven hundred sixty-four thousand, two hundred seventeen".