166645 has 4 divisors (see below), whose sum is σ = 199980. Its totient is φ = 133312.

The previous prime is 166643. The next prime is 166657. The reversal of 166645 is 546661.

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 88804 + 77841 = 298^2 + 279^2 .

It is a cyclic number.

It is not a de Polignac number, because 166645 - 2¹ = 166643 is a prime.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166643) 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, 16660 + ... + 16669.

It is an arithmetic number, because the mean of its divisors is an integer number (49995).

2¹⁶⁶⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

166645 is a deficient number, since it is larger than the sum of its proper divisors (33335).

166645 is an equidigital number, since it uses as much as digits as its factorization.

166645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33334.

The product of its digits is 4320, while the sum is 28.

The square root of 166645 is about 408.2217534625. The cubic root of 166645 is about 55.0297359863.

It can be divided in two parts, 1666 and 45, that added together give a triangular number (1711 = T₅₈).

The spelling of 166645 in words is "one hundred sixty-six thousand, six hundred forty-five".