216866945 has 8 divisors (see below), whose sum is σ = 262628520. Its totient is φ = 171901440.

The previous prime is 216866921. The next prime is 216867029. The reversal of 216866945 is 549668612.

It can be written as a sum of positive squares in 4 ways, for example, as 38056561 + 178810384 = 6169^2 + 13372^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-216866945 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 216866945.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 198416 + ... + 199505.

It is an arithmetic number, because the mean of its divisors is an integer number (32828565).

Almost surely, 2^216866945 is an apocalyptic number.

It is an amenable number.

216866945 is a deficient number, since it is larger than the sum of its proper divisors (45761575).

216866945 is a wasteful number, since it uses less digits than its factorization.

216866945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 398035.

The product of its digits is 622080, while the sum is 47.

The square root of 216866945 is about 14726.4029891892. The cubic root of 216866945 is about 600.8016552895.

The spelling of 216866945 in words is "two hundred sixteen million, eight hundred sixty-six thousand, nine hundred forty-five".