216690091 has 4 divisors (see below), whose sum is σ = 216926800. Its totient is φ = 216453384.

The previous prime is 216690077. The next prime is 216690119. The reversal of 216690091 is 190096612.

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 216690091 - 2⁹ = 216689579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216690191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 116976 + ... + 118813.

It is an arithmetic number, because the mean of its divisors is an integer number (54231700).

Almost surely, 2^216690091 is an apocalyptic number.

216690091 is a deficient number, since it is larger than the sum of its proper divisors (236709).

216690091 is an equidigital number, since it uses as much as digits as its factorization.

216690091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236708.

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 216690091 is about 14720.3971074153. The cubic root of 216690091 is about 600.6382938756.

The spelling of 216690091 in words is "two hundred sixteen million, six hundred ninety thousand, ninety-one".