16222721 has 4 divisors (see below), whose sum is σ = 16383444. Its totient is φ = 16062000.

The previous prime is 16222697. The next prime is 16222727. The reversal of 16222721 is 12722261.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 11316496 + 4906225 = 3364^2 + 2215^2 .

It is a cyclic number.

It is not a de Polignac number, because 16222721 - 2¹⁰ = 16221697 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (16222727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 80210 + ... + 80411.

It is an arithmetic number, because the mean of its divisors is an integer number (4095861).

Almost surely, 2^16222721 is an apocalyptic number.

It is an amenable number.

16222721 is a deficient number, since it is larger than the sum of its proper divisors (160723).

16222721 is a wasteful number, since it uses less digits than its factorization.

16222721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160722.

The product of its digits is 672, while the sum is 23.

The square root of 16222721 is about 4027.7439094361. The cubic root of 16222721 is about 253.1480383644.

Adding to 16222721 its reverse (12722261), we get a palindrome (28944982).

The spelling of 16222721 in words is "sixteen million, two hundred twenty-two thousand, seven hundred twenty-one".