216688387 has 4 divisors (see below), whose sum is σ = 216753616. Its totient is φ = 216623160.

The previous prime is 216688361. The next prime is 216688399. The reversal of 216688387 is 783886612.

216688387 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 216688387 - 2¹⁵ = 216655619 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 216688387.

It is not an unprimeable number, because it can be changed into a prime (216688337) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27348 + ... + 34369.

It is an arithmetic number, because the mean of its divisors is an integer number (54188404).

Almost surely, 2^216688387 is an apocalyptic number.

216688387 is a deficient number, since it is larger than the sum of its proper divisors (65229).

216688387 is an equidigital number, since it uses as much as digits as its factorization.

216688387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65228.

The product of its digits is 774144, while the sum is 49.

The square root of 216688387 is about 14720.3392284281. The cubic root of 216688387 is about 600.6367194453.

The spelling of 216688387 in words is "two hundred sixteen million, six hundred eighty-eight thousand, three hundred eighty-seven".