16791721 has 2 divisors, whose sum is σ = 16791722. Its totient is φ = 16791720.

The previous prime is 16791707. The next prime is 16791727. The reversal of 16791721 is 12719761.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16516096 + 275625 = 4064^2 + 525^2 .

It is an emirp because it is prime and its reverse (12719761) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16791721 - 2¹⁵ = 16758953 is a prime.

It is equal to p_1078756 and since 16791721 and 1078756 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (16791727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8395860 + 8395861.

It is an arithmetic number, because the mean of its divisors is an integer number (8395861).

Almost surely, 2^16791721 is an apocalyptic number.

It is an amenable number.

16791721 is a deficient number, since it is larger than the sum of its proper divisors (1).

16791721 is an equidigital number, since it uses as much as digits as its factorization.

16791721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5292, while the sum is 34.

The square root of 16791721 is about 4097.7702473418. The cubic root of 16791721 is about 256.0737549939.

The spelling of 16791721 in words is "sixteen million, seven hundred ninety-one thousand, seven hundred twenty-one".