166166981 has 2 divisors, whose sum is σ = 166166982. Its totient is φ = 166166980.

The previous prime is 166166977. The next prime is 166167077. The reversal of 166166981 is 189661661.

166166981 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., 163072900 + 3094081 = 12770^2 + 1759^2 .

It is a cyclic number.

It is not a de Polignac number, because 166166981 - 2² = 166166977 is a prime.

It is a super-2 number, since 2×166166981² = 55222931149308722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166166971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83083490 + 83083491.

It is an arithmetic number, because the mean of its divisors is an integer number (83083491).

Almost surely, 2^166166981 is an apocalyptic number.

It is an amenable number.

166166981 is a deficient number, since it is larger than the sum of its proper divisors (1).

166166981 is an equidigital number, since it uses as much as digits as its factorization.

166166981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312, while the sum is 44.

The square root of 166166981 is about 12890.5772174872. The cubic root of 166166981 is about 549.7706823628.

The spelling of 166166981 in words is "one hundred sixty-six million, one hundred sixty-six thousand, nine hundred eighty-one".