217156812 has 24 divisors (see below), whose sum is σ = 507640896. Its totient is φ = 72251088.

The previous prime is 217156789. The next prime is 217156817. The reversal of 217156812 is 218651712.

217156812 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a zygodrome in base 2.

It is not an unprimeable number, because it can be changed into a prime (217156817) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9978 + ... + 23105.

It is an arithmetic number, because the mean of its divisors is an integer number (21151704).

Almost surely, 2^217156812 is an apocalyptic number.

It is an amenable number.

217156812 is an abundant number, since it is smaller than the sum of its proper divisors (290484084).

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

217156812 is a wasteful number, since it uses less digits than its factorization.

217156812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33637 (or 33635 counting only the distinct ones).

The product of its digits is 6720, while the sum is 33.

The square root of 217156812 is about 14736.2414475334. The cubic root of 217156812 is about 601.0692157200.

The spelling of 217156812 in words is "two hundred seventeen million, one hundred fifty-six thousand, eight hundred twelve".