216540823 has 2 divisors, whose sum is σ = 216540824. Its totient is φ = 216540822.

The previous prime is 216540811. The next prime is 216540887. The reversal of 216540823 is 328045612.

216540823 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216540823 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216540223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108270411 + 108270412.

It is an arithmetic number, because the mean of its divisors is an integer number (108270412).

Almost surely, 2^216540823 is an apocalyptic number.

216540823 is a deficient number, since it is larger than the sum of its proper divisors (1).

216540823 is an equidigital number, since it uses as much as digits as its factorization.

216540823 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11520, while the sum is 31.

The square root of 216540823 is about 14715.3261261856. The cubic root of 216540823 is about 600.5003446797.

The spelling of 216540823 in words is "two hundred sixteen million, five hundred forty thousand, eight hundred twenty-three".