166851868691 has 2 divisors, whose sum is σ = 166851868692. Its totient is φ = 166851868690.

The previous prime is 166851868657. The next prime is 166851868699. The reversal of 166851868691 is 196868158661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 166851868691 - 2⁶ = 166851868627 is a prime.

It is not a weakly prime, because it can be changed into another prime (166851868699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83425934345 + 83425934346.

It is an arithmetic number, because the mean of its divisors is an integer number (83425934346).

Almost surely, 2^166851868691 is an apocalyptic number.

166851868691 is a deficient number, since it is larger than the sum of its proper divisors (1).

166851868691 is an equidigital number, since it uses as much as digits as its factorization.

166851868691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 29859840, while the sum is 65.

The spelling of 166851868691 in words is "one hundred sixty-six billion, eight hundred fifty-one million, eight hundred sixty-eight thousand, six hundred ninety-one".