216658981 has 16 divisors (see below), whose sum is σ = 270471168. Its totient is φ = 168606000.

The previous prime is 216658979. The next prime is 216659041. The reversal of 216658981 is 189856612.

It is a cyclic number.

It is not a de Polignac number, because 216658981 - 2¹ = 216658979 is a prime.

It is a super-2 number, since 2×216658981² = 93882228095916722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216659981) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 83656 + ... + 86206.

It is an arithmetic number, because the mean of its divisors is an integer number (16904448).

Almost surely, 2^216658981 is an apocalyptic number.

It is an amenable number.

216658981 is a deficient number, since it is larger than the sum of its proper divisors (53812187).

216658981 is a wasteful number, since it uses less digits than its factorization.

216658981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3672.

The product of its digits is 207360, while the sum is 46.

The square root of 216658981 is about 14719.3403724488. The cubic root of 216658981 is about 600.6095481347.

The spelling of 216658981 in words is "two hundred sixteen million, six hundred fifty-eight thousand, nine hundred eighty-one".