216821806 has 32 divisors (see below), whose sum is σ = 356774400. Its totient is φ = 98431200.

The previous prime is 216821789. The next prime is 216821807. The reversal of 216821806 is 608128612.

216821806 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216821807) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 165751 + ... + 167053.

It is an arithmetic number, because the mean of its divisors is an integer number (11149200).

Almost surely, 2^216821806 is an apocalyptic number.

216821806 is a deficient number, since it is larger than the sum of its proper divisors (139952594).

216821806 is a wasteful number, since it uses less digits than its factorization.

216821806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1504.

The product of its (nonzero) digits is 9216, while the sum is 34.

The square root of 216821806 is about 14724.8703220096. The cubic root of 216821806 is about 600.7599684882.

The spelling of 216821806 in words is "two hundred sixteen million, eight hundred twenty-one thousand, eight hundred six".