166121217 has 12 divisors (see below), whose sum is σ = 245805924. Its totient is φ = 108046080.

The previous prime is 166121213. The next prime is 166121227. The reversal of 166121217 is 712121661.

It is a happy number.

166121217 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 85821696 + 80299521 = 9264^2 + 8961^2 .

It is not a de Polignac number, because 166121217 - 2² = 166121213 is a prime.

It is a super-2 number, since 2×166121217² = 55192517475122178, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (166121213) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 224728 + ... + 225465.

It is an arithmetic number, because the mean of its divisors is an integer number (20483827).

Almost surely, 2^166121217 is an apocalyptic number.

It is an amenable number.

166121217 is a deficient number, since it is larger than the sum of its proper divisors (79684707).

166121217 is a wasteful number, since it uses less digits than its factorization.

166121217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 450240 (or 450237 counting only the distinct ones).

The product of its digits is 1008, while the sum is 27.

The square root of 166121217 is about 12888.8020001861. The cubic root of 166121217 is about 549.7202070007.

Adding to 166121217 its reverse (712121661), we get a palindrome (878242878).

The spelling of 166121217 in words is "one hundred sixty-six million, one hundred twenty-one thousand, two hundred seventeen".