166912021 has 4 divisors (see below), whose sum is σ = 167604844. Its totient is φ = 166219200.

The previous prime is 166912019. The next prime is 166912037. The reversal of 166912021 is 120219661.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 129640996 + 37271025 = 11386^2 + 6105^2 .

It is a cyclic number.

It is not a de Polignac number, because 166912021 - 2¹ = 166912019 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166912051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 346050 + ... + 346531.

It is an arithmetic number, because the mean of its divisors is an integer number (41901211).

Almost surely, 2^166912021 is an apocalyptic number.

It is an amenable number.

166912021 is a deficient number, since it is larger than the sum of its proper divisors (692823).

166912021 is an equidigital number, since it uses as much as digits as its factorization.

166912021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 692822.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 166912021 is about 12919.4435251678. The cubic root of 166912021 is about 550.5911231291.

The spelling of 166912021 in words is "one hundred sixty-six million, nine hundred twelve thousand, twenty-one".