2166321 has 8 divisors (see below), whose sum is σ = 2898144. Its totient is φ = 1439360.

The previous prime is 2166319. The next prime is 2166403. The reversal of 2166321 is 1236612.

It is a happy number.

2166321 is a nontrivial binomial coefficient, being equal to C(2082, 2).

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 2166321 - 2¹ = 2166319 is a prime.

2166321 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (2166121) 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, 1 + ... + 2081.

It is an arithmetic number, because the mean of its divisors is an integer number (362268).

2^2166321 is an apocalyptic number.

2166321 is the 2081-st triangular number and also the 1041-st hexagonal number.

It is an amenable number.

2166321 is a deficient number, since it is larger than the sum of its proper divisors (731823).

2166321 is a wasteful number, since it uses less digits than its factorization.

2166321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2431.

The product of its digits is 432, while the sum is 21.

The square root of 2166321 is about 1471.8427225760. The cubic root of 2166321 is about 129.3920528760.

The spelling of 2166321 in words is "two million, one hundred sixty-six thousand, three hundred twenty-one".