216540811 has 2 divisors, whose sum is σ = 216540812. Its totient is φ = 216540810.

The previous prime is 216540809. The next prime is 216540823. The reversal of 216540811 is 118045612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 216540811 - 2¹ = 216540809 is a prime.

Together with 216540809, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 216540811.

It is not a weakly prime, because it can be changed into another prime (216540011) 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 as a sum of consecutive naturals, namely, 108270405 + 108270406.

It is an arithmetic number, because the mean of its divisors is an integer number (108270406).

Almost surely, 2^216540811 is an apocalyptic number.

216540811 is a deficient number, since it is larger than the sum of its proper divisors (1).

216540811 is an equidigital number, since it uses as much as digits as its factorization.

216540811 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 216540811 is about 14715.3257184474. The cubic root of 216540811 is about 600.5003335871.

The spelling of 216540811 in words is "two hundred sixteen million, five hundred forty thousand, eight hundred eleven".