16721819 has 2 divisors, whose sum is σ = 16721820. Its totient is φ = 16721818.

The previous prime is 16721773. The next prime is 16721821. The reversal of 16721819 is 91812761.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16721819 is a prime.

It is a super-2 number, since 2×16721819² = 559238461337522, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 16721821, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (16721899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8360909 + 8360910.

It is an arithmetic number, because the mean of its divisors is an integer number (8360910).

Almost surely, 2^16721819 is an apocalyptic number.

16721819 is a deficient number, since it is larger than the sum of its proper divisors (1).

16721819 is an equidigital number, since it uses as much as digits as its factorization.

16721819 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6048, while the sum is 35.

The square root of 16721819 is about 4089.2320794985. The cubic root of 16721819 is about 255.7179255970.

The spelling of 16721819 in words is "sixteen million, seven hundred twenty-one thousand, eight hundred nineteen".