166521 has 8 divisors (see below), whose sum is σ = 226944. Its totient is φ = 108560.

The previous prime is 166487. The next prime is 166541. The reversal of 166521 is 125661.

It is a happy number.

166521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 166521 - 2⁶ = 166457 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 166521.

It is not an unprimeable number, because it can be changed into a prime (166541) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 450 + ... + 731.

It is an arithmetic number, because the mean of its divisors is an integer number (28368).

2¹⁶⁶⁵²¹ is an apocalyptic number.

It is an amenable number.

166521 is a deficient number, since it is larger than the sum of its proper divisors (60423).

166521 is a wasteful number, since it uses less digits than its factorization.

166521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1231.

The product of its digits is 360, while the sum is 21.

The square root of 166521 is about 408.0698469625. The cubic root of 166521 is about 55.0160834506.

It can be divided in two parts, 16652 and 1, that added together give a triangular number (16653 = T₁₈₂).

The spelling of 166521 in words is "one hundred sixty-six thousand, five hundred twenty-one".