166123561 has 2 divisors, whose sum is σ = 166123562. Its totient is φ = 166123560.

The previous prime is 166123543. The next prime is 166123667. The reversal of 166123561 is 165321661.

166123561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 159264400 + 6859161 = 12620^2 + 2619^2 .

It is a cyclic number.

It is not a de Polignac number, because 166123561 - 2²³ = 157734953 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (166123501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83061780 + 83061781.

It is an arithmetic number, because the mean of its divisors is an integer number (83061781).

Almost surely, 2^166123561 is an apocalyptic number.

It is an amenable number.

166123561 is a deficient number, since it is larger than the sum of its proper divisors (1).

166123561 is an equidigital number, since it uses as much as digits as its factorization.

166123561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6480, while the sum is 31.

The square root of 166123561 is about 12888.8929315128. The cubic root of 166123561 is about 549.7227925386.

The spelling of 166123561 in words is "one hundred sixty-six million, one hundred twenty-three thousand, five hundred sixty-one".