166226628681 has 45 divisors (see below), whose sum is σ = 251629603621. Its totient is φ = 109357338816.

The previous prime is 166226628679. The next prime is 166226628731. The reversal of 166226628681 is 186826622661.

The square root of 166226628681 is 407709.

It is a perfect power (a square), and thus also a powerful number.

166226628681 is a `hidden beast` number, since 1 + 6 + 6 + 2 + 2 + 6 + 628 + 6 + 8 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 7338681 + 166219290000 = 2709^2 + 407700^2 .

It is not a de Polignac number, because 166226628681 - 2¹ = 166226628679 is a prime.

It is a super-2 number, since 2×166226628681² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (166226628671) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 326574655 + ... + 326575163.

Almost surely, 2^166226628681 is an apocalyptic number.

166226628681 is the 407709-th square number.

166226628681 is the 203855-th centered octagonal number.

It is an amenable number.

166226628681 is a deficient number, since it is larger than the sum of its proper divisors (85402974940).

166226628681 is an frugal number, since it uses more digits than its factorization.

166226628681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1208 (or 601 counting only the distinct ones).

The product of its digits is 3981312, while the sum is 54.

The spelling of 166226628681 in words is "one hundred sixty-six billion, two hundred twenty-six million, six hundred twenty-eight thousand, six hundred eighty-one".