216521233 has 2 divisors, whose sum is σ = 216521234. Its totient is φ = 216521232.

The previous prime is 216521219. The next prime is 216521251. The reversal of 216521233 is 332125612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 146095569 + 70425664 = 12087^2 + 8392^2 .

It is a cyclic number.

It is not a de Polignac number, because 216521233 - 2²¹ = 214424081 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 216521198 and 216521207.

It is not a weakly prime, because it can be changed into another prime (216521203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108260616 + 108260617.

It is an arithmetic number, because the mean of its divisors is an integer number (108260617).

Almost surely, 2^216521233 is an apocalyptic number.

It is an amenable number.

216521233 is a deficient number, since it is larger than the sum of its proper divisors (1).

216521233 is an equidigital number, since it uses as much as digits as its factorization.

216521233 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2160, while the sum is 25.

The square root of 216521233 is about 14714.6604785839. The cubic root of 216521233 is about 600.4822354592.

Adding to 216521233 its reverse (332125612), we get a palindrome (548646845).

The spelling of 216521233 in words is "two hundred sixteen million, five hundred twenty-one thousand, two hundred thirty-three".