2116165721 has 16 divisors (see below), whose sum is σ = 2184536448. Its totient is φ = 2049062400.

The previous prime is 2116165651. The next prime is 2116165739. The reversal of 2116165721 is 1275616112.

It is a cyclic number.

It is not a de Polignac number, because 2116165721 - 2³⁰ = 1042423897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2116165781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3144041 + ... + 3144713.

It is an arithmetic number, because the mean of its divisors is an integer number (136533528).

Almost surely, 2^2116165721 is an apocalyptic number.

It is an amenable number.

2116165721 is a deficient number, since it is larger than the sum of its proper divisors (68370727).

2116165721 is an equidigital number, since it uses as much as digits as its factorization.

2116165721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1472.

The product of its digits is 5040, while the sum is 32.

The square root of 2116165721 is about 46001.8012799499. The cubic root of 2116165721 is about 1283.8567192355.

The spelling of 2116165721 in words is "two billion, one hundred sixteen million, one hundred sixty-five thousand, seven hundred twenty-one".