16665321 has 32 divisors (see below), whose sum is σ = 24772608. Its totient is φ = 9918720.

The previous prime is 16665301. The next prime is 16665347. The reversal of 16665321 is 12356661.

It is not a de Polignac number, because 16665321 - 2⁵ = 16665289 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (16665301) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 131160 + ... + 131286.

It is an arithmetic number, because the mean of its divisors is an integer number (774144).

Almost surely, 2^16665321 is an apocalyptic number.

It is an amenable number.

16665321 is a deficient number, since it is larger than the sum of its proper divisors (8107287).

16665321 is a wasteful number, since it uses less digits than its factorization.

16665321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 261.

The product of its digits is 6480, while the sum is 30.

The square root of 16665321 is about 4082.3180914769. The cubic root of 16665321 is about 255.4296026324.

The spelling of 16665321 in words is "sixteen million, six hundred sixty-five thousand, three hundred twenty-one".