166420081 has 4 divisors (see below), whose sum is σ = 166461952. Its totient is φ = 166378212.

The previous prime is 166420073. The next prime is 166420097. The reversal of 166420081 is 180024661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 180024661 = 89 ⋅2022749.

It is a cyclic number.

It is not a de Polignac number, because 166420081 - 2³ = 166420073 is a prime.

It is a super-3 number, since 3×166420081³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166426081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14265 + ... + 23158.

It is an arithmetic number, because the mean of its divisors is an integer number (41615488).

Almost surely, 2^166420081 is an apocalyptic number.

It is an amenable number.

166420081 is a deficient number, since it is larger than the sum of its proper divisors (41871).

166420081 is an equidigital number, since it uses as much as digits as its factorization.

166420081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41870.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 166420081 is about 12900.3907305167. The cubic root of 166420081 is about 550.0496715470.

The spelling of 166420081 in words is "one hundred sixty-six million, four hundred twenty thousand, eighty-one".