166321217 has 4 divisors (see below), whose sum is σ = 176104836. Its totient is φ = 156537600.

The previous prime is 166321213. The next prime is 166321219. The reversal of 166321217 is 712123661.

166321217 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 135396496 + 30924721 = 11636^2 + 5561^2 .

It is a cyclic number.

It is not a de Polignac number, because 166321217 - 2² = 166321213 is a prime.

It is a super-2 number, since 2×166321217² = 55325494448722178, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 166321217.

It is not an unprimeable number, because it can be changed into a prime (166321213) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4891784 + ... + 4891817.

It is an arithmetic number, because the mean of its divisors is an integer number (44026209).

Almost surely, 2^166321217 is an apocalyptic number.

166321217 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

166321217 is a deficient number, since it is larger than the sum of its proper divisors (9783619).

166321217 is an equidigital number, since it uses as much as digits as its factorization.

166321217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9783618.

The product of its digits is 3024, while the sum is 29.

The square root of 166321217 is about 12896.5583393400. The cubic root of 166321217 is about 549.9407285990.

Adding to 166321217 its reverse (712123661), we get a palindrome (878444878).

The spelling of 166321217 in words is "one hundred sixty-six million, three hundred twenty-one thousand, two hundred seventeen".