216891558 has 144 divisors (see below), whose sum is σ = 546751296. Its totient is φ = 62000640.

The previous prime is 216891553. The next prime is 216891583. The reversal of 216891558 is 855198612.

It is a happy number.

216891558 is a `hidden beast` number, since 2 + 1 + 6 + 8 + 91 + 558 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216891553) by changing a digit.

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 71 ways as a sum of consecutive naturals, for example, 4614691 + ... + 4614737.

It is an arithmetic number, because the mean of its divisors is an integer number (3796884).

Almost surely, 2^216891558 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 216891558, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (273375648).

216891558 is an abundant number, since it is smaller than the sum of its proper divisors (329859738).

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

216891558 is a wasteful number, since it uses less digits than its factorization.

216891558 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159 (or 143 counting only the distinct ones).

The product of its digits is 172800, while the sum is 45.

The square root of 216891558 is about 14727.2386413747. The cubic root of 216891558 is about 600.8243834677.

The spelling of 216891558 in words is "two hundred sixteen million, eight hundred ninety-one thousand, five hundred fifty-eight".