216445891 has 8 divisors (see below), whose sum is σ = 227993600. Its totient is φ = 204913800.

The previous prime is 216445883. The next prime is 216445909. The reversal of 216445891 is 198544612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 216445891 - 2³ = 216445883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216445811) 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, 34150 + ... + 39988.

It is an arithmetic number, because the mean of its divisors is an integer number (28499200).

Almost surely, 2^216445891 is an apocalyptic number.

216445891 is a deficient number, since it is larger than the sum of its proper divisors (11547709).

216445891 is a wasteful number, since it uses less digits than its factorization.

216445891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7809.

The product of its digits is 69120, while the sum is 40.

The square root of 216445891 is about 14712.1001559940. The cubic root of 216445891 is about 600.4125782706.

The spelling of 216445891 in words is "two hundred sixteen million, four hundred forty-five thousand, eight hundred ninety-one".