216188398721 has 2 divisors, whose sum is σ = 216188398722. Its totient is φ = 216188398720.

The previous prime is 216188398663. The next prime is 216188398739. The reversal of 216188398721 is 127893881612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 177039819121 + 39148579600 = 420761^2 + 197860^2 .

It is a cyclic number.

It is not a de Polignac number, because 216188398721 - 2²² = 216184204417 is a prime.

It is not a weakly prime, because it can be changed into another prime (216188391721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108094199360 + 108094199361.

It is an arithmetic number, because the mean of its divisors is an integer number (108094199361).

Almost surely, 2^216188398721 is an apocalyptic number.

It is an amenable number.

216188398721 is a deficient number, since it is larger than the sum of its proper divisors (1).

216188398721 is an equidigital number, since it uses as much as digits as its factorization.

216188398721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2322432, while the sum is 56.

The spelling of 216188398721 in words is "two hundred sixteen billion, one hundred eighty-eight million, three hundred ninety-eight thousand, seven hundred twenty-one".