16872221 has 2 divisors, whose sum is σ = 16872222. Its totient is φ = 16872220.

The previous prime is 16872199. The next prime is 16872223. The reversal of 16872221 is 12227861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14546596 + 2325625 = 3814^2 + 1525^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16872221 is a prime.

It is a Sophie Germain prime.

Together with 16872223, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16872223) 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 as a sum of consecutive naturals, namely, 8436110 + 8436111.

It is an arithmetic number, because the mean of its divisors is an integer number (8436111).

Almost surely, 2^16872221 is an apocalyptic number.

It is an amenable number.

16872221 is a deficient number, since it is larger than the sum of its proper divisors (1).

16872221 is an equidigital number, since it uses as much as digits as its factorization.

16872221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2688, while the sum is 29.

The square root of 16872221 is about 4107.5809182535. The cubic root of 16872221 is about 256.4823111599.

The spelling of 16872221 in words is "sixteen million, eight hundred seventy-two thousand, two hundred twenty-one".