216216666 has 12 divisors (see below), whose sum is σ = 468469482. Its totient is φ = 72072216.

The previous prime is 216216647. The next prime is 216216667. The reversal of 216216666 is 666612612.

It is a happy number.

216216666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 159289641 + 56927025 = 12621^2 + 7545^2 .

It is a nude number because it is divisible by every one of its digits.

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 216216666.

It is not an unprimeable number, because it can be changed into a prime (216216667) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6006001 + ... + 6006036.

Almost surely, 2^216216666 is an apocalyptic number.

216216666 is an abundant number, since it is smaller than the sum of its proper divisors (252252816).

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

216216666 is a wasteful number, since it uses less digits than its factorization.

216216666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12012045 (or 12012042 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 216216666 is about 14704.3077361704. The cubic root of 216216666 is about 600.2005496256.

The spelling of 216216666 in words is "two hundred sixteen million, two hundred sixteen thousand, six hundred sixty-six".