16221643 has 4 divisors (see below), whose sum is σ = 16781040. Its totient is φ = 15662248.

The previous prime is 16221641. The next prime is 16221659. The reversal of 16221643 is 34612261.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 16221643 - 2¹ = 16221641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16221641) 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, 279655 + ... + 279712.

It is an arithmetic number, because the mean of its divisors is an integer number (4195260).

Almost surely, 2^16221643 is an apocalyptic number.

16221643 is a deficient number, since it is larger than the sum of its proper divisors (559397).

16221643 is an equidigital number, since it uses as much as digits as its factorization.

16221643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 559396.

The product of its digits is 1728, while the sum is 25.

The square root of 16221643 is about 4027.6100853980. The cubic root of 16221643 is about 253.1424310102.

The spelling of 16221643 in words is "sixteen million, two hundred twenty-one thousand, six hundred forty-three".