166212021 has 16 divisors (see below), whose sum is σ = 232407360. Its totient is φ = 105517440.

The previous prime is 166211993. The next prime is 166212031. The reversal of 166212021 is 120212661.

166212021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 166212021 - 2⁵ = 166211989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166212031) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6735 + ... + 19436.

It is an arithmetic number, because the mean of its divisors is an integer number (14525460).

Almost surely, 2^166212021 is an apocalyptic number.

It is an amenable number.

166212021 is a deficient number, since it is larger than the sum of its proper divisors (66195339).

166212021 is a wasteful number, since it uses less digits than its factorization.

166212021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26276.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 166212021 is about 12892.3241116565. The cubic root of 166212021 is about 549.8203501417.

Adding to 166212021 its reverse (120212661), we get a palindrome (286424682).

The spelling of 166212021 in words is "one hundred sixty-six million, two hundred twelve thousand, twenty-one".