16667221 has 4 divisors (see below), whose sum is σ = 16732332. Its totient is φ = 16602112.

The previous prime is 16667173. The next prime is 16667263. The reversal of 16667221 is 12276661.

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 15132100 + 1535121 = 3890^2 + 1239^2 .

It is a cyclic number.

It is not a de Polignac number, because 16667221 - 2¹⁹ = 16142933 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16667291) 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, 32170 + ... + 32683.

It is an arithmetic number, because the mean of its divisors is an integer number (4183083).

Almost surely, 2^16667221 is an apocalyptic number.

It is an amenable number.

16667221 is a deficient number, since it is larger than the sum of its proper divisors (65111).

16667221 is an equidigital number, since it uses as much as digits as its factorization.

16667221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65110.

The product of its digits is 6048, while the sum is 31.

The square root of 16667221 is about 4082.5507957648. The cubic root of 16667221 is about 255.4393093722.

The spelling of 16667221 in words is "sixteen million, six hundred sixty-seven thousand, two hundred twenty-one".