216689281 has 8 divisors (see below), whose sum is σ = 232398720. Its totient is φ = 201410352.

The previous prime is 216689269. The next prime is 216689299. The reversal of 216689281 is 182986612.

It is a happy number.

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 216689281 - 2¹⁵ = 216656513 is a prime.

It is a super-2 number, since 2×216689281² = 93908489000593922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216689251) 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 7 ways as a sum of consecutive naturals, for example, 106585 + ... + 108598.

It is an arithmetic number, because the mean of its divisors is an integer number (29049840).

Almost surely, 2^216689281 is an apocalyptic number.

It is an amenable number.

216689281 is a deficient number, since it is larger than the sum of its proper divisors (15709439).

216689281 is a wasteful number, since it uses less digits than its factorization.

216689281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215255.

The product of its digits is 82944, while the sum is 43.

The square root of 216689281 is about 14720.3695945448. The cubic root of 216689281 is about 600.6375454678.

The spelling of 216689281 in words is "two hundred sixteen million, six hundred eighty-nine thousand, two hundred eighty-one".