16316509721 has 2 divisors, whose sum is σ = 16316509722. Its totient is φ = 16316509720.

The previous prime is 16316509709. The next prime is 16316509753. The reversal of 16316509721 is 12790561361.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16316485696 + 24025 = 127736^2 + 155^2 .

It is a cyclic number.

It is not a de Polignac number, because 16316509721 - 2¹⁰ = 16316508697 is a prime.

It is not a weakly prime, because it can be changed into another prime (16316509771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8158254860 + 8158254861.

It is an arithmetic number, because the mean of its divisors is an integer number (8158254861).

Almost surely, 2^16316509721 is an apocalyptic number.

It is an amenable number.

16316509721 is a deficient number, since it is larger than the sum of its proper divisors (1).

16316509721 is an equidigital number, since it uses as much as digits as its factorization.

16316509721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 68040, while the sum is 41.

The spelling of 16316509721 in words is "sixteen billion, three hundred sixteen million, five hundred nine thousand, seven hundred twenty-one".