216403666 has 8 divisors (see below), whose sum is σ = 325899504. Its totient is φ = 107770500.

The previous prime is 216403633. The next prime is 216403697. The reversal of 216403666 is 666304612.

216403666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

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, 215040 + ... + 216043.

It is an arithmetic number, because the mean of its divisors is an integer number (40737438).

Almost surely, 2^216403666 is an apocalyptic number.

216403666 is a deficient number, since it is larger than the sum of its proper divisors (109495838).

216403666 is a wasteful number, since it uses less digits than its factorization.

216403666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 431336.

The product of its (nonzero) digits is 31104, while the sum is 34.

The square root of 216403666 is about 14710.6650427504. The cubic root of 216403666 is about 600.3735322227.

The spelling of 216403666 in words is "two hundred sixteen million, four hundred three thousand, six hundred sixty-six".