216872591 has 4 divisors (see below), whose sum is σ = 233555112. Its totient is φ = 200190072.

The previous prime is 216872573. The next prime is 216872599. The reversal of 216872591 is 195278612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216872591 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216872599) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8341241 + ... + 8341266.

It is an arithmetic number, because the mean of its divisors is an integer number (58388778).

Almost surely, 2^216872591 is an apocalyptic number.

216872591 is a deficient number, since it is larger than the sum of its proper divisors (16682521).

216872591 is a wasteful number, since it uses less digits than its factorization.

216872591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16682520.

The product of its digits is 60480, while the sum is 41.

The square root of 216872591 is about 14726.5946844476. The cubic root of 216872591 is about 600.8068690804.

The spelling of 216872591 in words is "two hundred sixteen million, eight hundred seventy-two thousand, five hundred ninety-one".