216399856 has 40 divisors (see below), whose sum is σ = 435351600. Its totient is φ = 104079360.

The previous prime is 216399853. The next prime is 216399863. The reversal of 216399856 is 658993612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216399853) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 152880 + ... + 154288.

It is an arithmetic number, because the mean of its divisors is an integer number (10883790).

Almost surely, 2^216399856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 216399856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (217675800).

216399856 is an abundant number, since it is smaller than the sum of its proper divisors (218951744).

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

216399856 is a wasteful number, since it uses less digits than its factorization.

216399856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1777 (or 1771 counting only the distinct ones).

The product of its digits is 699840, while the sum is 49.

The square root of 216399856 is about 14710.5355442961. The cubic root of 216399856 is about 600.3700088126.

The spelling of 216399856 in words is "two hundred sixteen million, three hundred ninety-nine thousand, eight hundred fifty-six".