216091765 has 4 divisors (see below), whose sum is σ = 259310124. Its totient is φ = 172873408.

The previous prime is 216091741. The next prime is 216091783. The reversal of 216091765 is 567190612.

216091765 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 can be written as a sum of positive squares in 2 ways, for example, as 125955729 + 90136036 = 11223^2 + 9494^2 .

It is a cyclic number.

It is not a de Polignac number, because 216091765 - 2¹³ = 216083573 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21609172 + ... + 21609181.

It is an arithmetic number, because the mean of its divisors is an integer number (64827531).

Almost surely, 2^216091765 is an apocalyptic number.

It is an amenable number.

216091765 is a deficient number, since it is larger than the sum of its proper divisors (43218359).

216091765 is an equidigital number, since it uses as much as digits as its factorization.

216091765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43218358.

The product of its (nonzero) digits is 22680, while the sum is 37.

The square root of 216091765 is about 14700.0600338910. The cubic root of 216091765 is about 600.0849555629.

The spelling of 216091765 in words is "two hundred sixteen million, ninety-one thousand, seven hundred sixty-five".