216988865 has 4 divisors (see below), whose sum is σ = 260386644. Its totient is φ = 173591088.

The previous prime is 216988861. The next prime is 216988907. The reversal of 216988865 is 568889612.

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 28558336 + 188430529 = 5344^2 + 13727^2 .

It is a cyclic number.

It is not a de Polignac number, because 216988865 - 2² = 216988861 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216988861) 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, 21698882 + ... + 21698891.

It is an arithmetic number, because the mean of its divisors is an integer number (65096661).

Almost surely, 2^216988865 is an apocalyptic number.

It is an amenable number.

216988865 is a deficient number, since it is larger than the sum of its proper divisors (43397779).

216988865 is an equidigital number, since it uses as much as digits as its factorization.

216988865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43397778.

The product of its digits is 1658880, while the sum is 53.

The square root of 216988865 is about 14730.5419112808. The cubic root of 216988865 is about 600.9142220300.

The spelling of 216988865 in words is "two hundred sixteen million, nine hundred eighty-eight thousand, eight hundred sixty-five".