216391888 has 20 divisors (see below), whose sum is σ = 426134308. Its totient is φ = 106421760.

The previous prime is 216391837. The next prime is 216391907. The reversal of 216391888 is 888193612.

It can be written as a sum of positive squares in 2 ways, for example, as 60341824 + 156050064 = 7768^2 + 12492^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109881 + ... + 111832.

Almost surely, 2^216391888 is an apocalyptic number.

It is an amenable number.

216391888 is a deficient number, since it is larger than the sum of its proper divisors (209742420).

216391888 is a wasteful number, since it uses less digits than its factorization.

216391888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221782 (or 221776 counting only the distinct ones).

The product of its digits is 165888, while the sum is 46.

The square root of 216391888 is about 14710.2647154971. The cubic root of 216391888 is about 600.3626400354.

The spelling of 216391888 in words is "two hundred sixteen million, three hundred ninety-one thousand, eight hundred eighty-eight".