166666851557 has 2 divisors, whose sum is σ = 166666851558. Its totient is φ = 166666851556.

The previous prime is 166666851553. The next prime is 166666851563. The reversal of 166666851557 is 755158666661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 162738821281 + 3928030276 = 403409^2 + 62674^2 .

It is a cyclic number.

It is not a de Polignac number, because 166666851557 - 2² = 166666851553 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 166666851557.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166666851553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83333425778 + 83333425779.

It is an arithmetic number, because the mean of its divisors is an integer number (83333425779).

Almost surely, 2^166666851557 is an apocalyptic number.

It is an amenable number.

166666851557 is a deficient number, since it is larger than the sum of its proper divisors (1).

166666851557 is an equidigital number, since it uses as much as digits as its factorization.

166666851557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432000, while the sum is 62.

The spelling of 166666851557 in words is "one hundred sixty-six billion, six hundred sixty-six million, eight hundred fifty-one thousand, five hundred fifty-seven".