216678591 has 32 divisors (see below), whose sum is σ = 330513920. Its totient is φ = 140216832.

The previous prime is 216678587. The next prime is 216678611. The reversal of 216678591 is 195876612.

It is not a de Polignac number, because 216678591 - 2² = 216678587 is a prime.

It is a super-2 number, since 2×216678591² = 93899223595490562, which contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216678551) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 223590 + ... + 224556.

It is an arithmetic number, because the mean of its divisors is an integer number (10328560).

Almost surely, 2^216678591 is an apocalyptic number.

216678591 is a deficient number, since it is larger than the sum of its proper divisors (113835329).

216678591 is a wasteful number, since it uses less digits than its factorization.

216678591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1212 (or 1206 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The square root of 216678591 is about 14720.0064877703. The cubic root of 216678591 is about 600.6276681588.

The spelling of 216678591 in words is "two hundred sixteen million, six hundred seventy-eight thousand, five hundred ninety-one".