166221641 has 4 divisors (see below), whose sum is σ = 166330500. Its totient is φ = 166112784.

The previous prime is 166221637. The next prime is 166221647. The reversal of 166221641 is 146122661.

166221641 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, and also an emirpimes, since its reverse is a distinct semiprime: 146122661 = 149 ⋅980689.

It can be written as a sum of positive squares in 2 ways, for example, as 41229241 + 124992400 = 6421^2 + 11180^2 .

It is a cyclic number.

It is not a de Polignac number, because 166221641 - 2² = 166221637 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166221647) 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, 52106 + ... + 55203.

It is an arithmetic number, because the mean of its divisors is an integer number (41582625).

Almost surely, 2^166221641 is an apocalyptic number.

It is an amenable number.

166221641 is a deficient number, since it is larger than the sum of its proper divisors (108859).

166221641 is a wasteful number, since it uses less digits than its factorization.

166221641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108858.

The product of its digits is 3456, while the sum is 29.

The square root of 166221641 is about 12892.6971964752. The cubic root of 166221641 is about 549.8309574165.

The spelling of 166221641 in words is "one hundred sixty-six million, two hundred twenty-one thousand, six hundred forty-one".