16721155109 has 2 divisors, whose sum is σ = 16721155110. Its totient is φ = 16721155108.

The previous prime is 16721155097. The next prime is 16721155111. The reversal of 16721155109 is 90155112761.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11512646209 + 5208508900 = 107297^2 + 72170^2 .

It is a cyclic number.

It is not a de Polignac number, because 16721155109 - 2²⁸ = 16452719653 is a prime.

Together with 16721155111, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16721155159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8360577554 + 8360577555.

It is an arithmetic number, because the mean of its divisors is an integer number (8360577555).

Almost surely, 2^16721155109 is an apocalyptic number.

It is an amenable number.

16721155109 is a deficient number, since it is larger than the sum of its proper divisors (1).

16721155109 is an equidigital number, since it uses as much as digits as its factorization.

16721155109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18900, while the sum is 38.

The spelling of 16721155109 in words is "sixteen billion, seven hundred twenty-one million, one hundred fifty-five thousand, one hundred nine".