216428712721 has 16 divisors (see below), whose sum is σ = 236725448400. Its totient is φ = 196672785408.

The previous prime is 216428712707. The next prime is 216428712743. The reversal of 216428712721 is 127217824612.

It can be written as a sum of positive squares in 8 ways, for example, as 25459712721 + 190969000000 = 159561^2 + 437000^2 .

It is a cyclic number.

It is not a de Polignac number, because 216428712721 - 2⁷ = 216428712593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216428712791) 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, 143476 + ... + 673381.

It is an arithmetic number, because the mean of its divisors is an integer number (14795340525).

Almost surely, 2^216428712721 is an apocalyptic number.

It is an amenable number.

216428712721 is a deficient number, since it is larger than the sum of its proper divisors (20296735679).

216428712721 is a wasteful number, since it uses less digits than its factorization.

216428712721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 817188.

The product of its digits is 150528, while the sum is 43.

The spelling of 216428712721 in words is "two hundred sixteen billion, four hundred twenty-eight million, seven hundred twelve thousand, seven hundred twenty-one".