216821538833 has 2 divisors, whose sum is σ = 216821538834. Its totient is φ = 216821538832.

The previous prime is 216821538709. The next prime is 216821538853. The reversal of 216821538833 is 338835128612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 163629958144 + 53191580689 = 404512^2 + 230633^2 .

It is a cyclic number.

It is not a de Polignac number, because 216821538833 - 2³⁴ = 199641669649 is a prime.

It is not a weakly prime, because it can be changed into another prime (216821538853) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108410769416 + 108410769417.

It is an arithmetic number, because the mean of its divisors is an integer number (108410769417).

Almost surely, 2^216821538833 is an apocalyptic number.

It is an amenable number.

216821538833 is a deficient number, since it is larger than the sum of its proper divisors (1).

216821538833 is an equidigital number, since it uses as much as digits as its factorization.

216821538833 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1658880, while the sum is 50.

The spelling of 216821538833 in words is "two hundred sixteen billion, eight hundred twenty-one million, five hundred thirty-eight thousand, eight hundred thirty-three".