16138721 has 2 divisors, whose sum is σ = 16138722. Its totient is φ = 16138720.

The previous prime is 16138711. The next prime is 16138739. The reversal of 16138721 is 12783161.

16138721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16120225 + 18496 = 4015^2 + 136^2 .

It is an emirp because it is prime and its reverse (12783161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16138721 - 2²² = 11944417 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (16138711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8069360 + 8069361.

It is an arithmetic number, because the mean of its divisors is an integer number (8069361).

Almost surely, 2^16138721 is an apocalyptic number.

It is an amenable number.

16138721 is a deficient number, since it is larger than the sum of its proper divisors (1).

16138721 is an equidigital number, since it uses as much as digits as its factorization.

16138721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2016, while the sum is 29.

The square root of 16138721 is about 4017.3027020627. The cubic root of 16138721 is about 252.7103550470.

The spelling of 16138721 in words is "sixteen million, one hundred thirty-eight thousand, seven hundred twenty-one".