216168993 has 20 divisors (see below), whose sum is σ = 323581588. Its totient is φ = 143817120.

The previous prime is 216168989. The next prime is 216169007. The reversal of 216168993 is 399861612.

It is a happy number.

216168993 is a `hidden beast` number, since 21 + 616 + 8 + 9 + 9 + 3 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 76527504 + 139641489 = 8748^2 + 11817^2 .

It is not a de Polignac number, because 216168993 - 2² = 216168989 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (216168493) 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 19 ways as a sum of consecutive naturals, for example, 41355 + ... + 46287.

Almost surely, 2^216168993 is an apocalyptic number.

It is an amenable number.

216168993 is a deficient number, since it is larger than the sum of its proper divisors (107412595).

216168993 is an equidigital number, since it uses as much as digits as its factorization.

216168993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5486 (or 5477 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 216168993 is about 14702.6865912322. The cubic root of 216168993 is about 600.1564342104.

The spelling of 216168993 in words is "two hundred sixteen million, one hundred sixty-eight thousand, nine hundred ninety-three".