16721666 has 16 divisors (see below), whose sum is σ = 27081600. Its totient is φ = 7697808.

The previous prime is 16721657. The next prime is 16721671. The reversal of 16721666 is 66612761.

It is a super-2 number, since 2×16721666² = 559228227631112, which contains 22 as substring.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15575 + ... + 16613.

It is an arithmetic number, because the mean of its divisors is an integer number (1692600).

Almost surely, 2^16721666 is an apocalyptic number.

16721666 is a deficient number, since it is larger than the sum of its proper divisors (10359934).

16721666 is a wasteful number, since it uses less digits than its factorization.

16721666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1673.

The product of its digits is 18144, while the sum is 35.

The square root of 16721666 is about 4089.2133717868. The cubic root of 16721666 is about 255.7171456786.

The spelling of 16721666 in words is "sixteen million, seven hundred twenty-one thousand, six hundred sixty-six".