166859167781 has 2 divisors, whose sum is σ = 166859167782. Its totient is φ = 166859167780.

The previous prime is 166859167693. The next prime is 166859167793. The reversal of 166859167781 is 187761958661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 166815064900 + 44102881 = 408430^2 + 6641^2 .

It is a cyclic number.

It is not a de Polignac number, because 166859167781 - 2¹⁴ = 166859151397 is a prime.

It is a super-2 number, since 2×166859167781² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166859167081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83429583890 + 83429583891.

It is an arithmetic number, because the mean of its divisors is an integer number (83429583891).

Almost surely, 2^166859167781 is an apocalyptic number.

It is an amenable number.

166859167781 is a deficient number, since it is larger than the sum of its proper divisors (1).

166859167781 is an equidigital number, since it uses as much as digits as its factorization.

166859167781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30481920, while the sum is 65.

The spelling of 166859167781 in words is "one hundred sixty-six billion, eight hundred fifty-nine million, one hundred sixty-seven thousand, seven hundred eighty-one".