216391816 has 16 divisors (see below), whose sum is σ = 406065600. Its totient is φ = 108107664.

The previous prime is 216391801. The next prime is 216391837. The reversal of 216391816 is 618193612.

216391816 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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, 45 + ... + 20803.

It is an arithmetic number, because the mean of its divisors is an integer number (25379100).

Almost surely, 2^216391816 is an apocalyptic number.

It is an amenable number.

216391816 is a deficient number, since it is larger than the sum of its proper divisors (189673784).

216391816 is a wasteful number, since it uses less digits than its factorization.

216391816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22068 (or 22064 counting only the distinct ones).

The product of its digits is 15552, while the sum is 37.

The square root of 216391816 is about 14710.2622682262. The cubic root of 216391816 is about 600.3625734493.

The spelling of 216391816 in words is "two hundred sixteen million, three hundred ninety-one thousand, eight hundred sixteen".