16512721 has 2 divisors, whose sum is σ = 16512722. Its totient is φ = 16512720.

The previous prime is 16512719. The next prime is 16512757. The reversal of 16512721 is 12721561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16443025 + 69696 = 4055^2 + 264^2 .

It is a cyclic number.

It is not a de Polignac number, because 16512721 - 2¹ = 16512719 is a prime.

Together with 16512719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (16510721) 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, 8256360 + 8256361.

It is an arithmetic number, because the mean of its divisors is an integer number (8256361).

Almost surely, 2^16512721 is an apocalyptic number.

It is an amenable number.

16512721 is a deficient number, since it is larger than the sum of its proper divisors (1).

16512721 is an equidigital number, since it uses as much as digits as its factorization.

16512721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 840, while the sum is 25.

The square root of 16512721 is about 4063.5847474859. The cubic root of 16512721 is about 254.6475767224.

The spelling of 16512721 in words is "sixteen million, five hundred twelve thousand, seven hundred twenty-one".