216445866 has 64 divisors (see below), whose sum is σ = 541900800. Its totient is φ = 56108736.

The previous prime is 216445841. The next prime is 216445871. The reversal of 216445866 is 668544612.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28855 + ... + 35573.

It is an arithmetic number, because the mean of its divisors is an integer number (8467200).

Almost surely, 2^216445866 is an apocalyptic number.

216445866 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 216445866, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (270950400).

216445866 is an abundant number, since it is smaller than the sum of its proper divisors (325454934).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

216445866 is a wasteful number, since it uses less digits than its factorization.

216445866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6803.

The product of its digits is 276480, while the sum is 42.

The square root of 216445866 is about 14712.0993063533. The cubic root of 216445866 is about 600.4125551543.

The spelling of 216445866 in words is "two hundred sixteen million, four hundred forty-five thousand, eight hundred sixty-six".