216772581 has 4 divisors (see below), whose sum is σ = 289030112. Its totient is φ = 144515052.

The previous prime is 216772579. The next prime is 216772607. The reversal of 216772581 is 185277612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 216772581 - 2¹ = 216772579 is a prime.

It is a super-2 number, since 2×216772581² = 93980703746803122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216772531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36128761 + ... + 36128766.

It is an arithmetic number, because the mean of its divisors is an integer number (72257528).

Almost surely, 2^216772581 is an apocalyptic number.

It is an amenable number.

216772581 is a deficient number, since it is larger than the sum of its proper divisors (72257531).

216772581 is an equidigital number, since it uses as much as digits as its factorization.

216772581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72257530.

The product of its digits is 47040, while the sum is 39.

The square root of 216772581 is about 14723.1987353292. The cubic root of 216772581 is about 600.7145015858.

The spelling of 216772581 in words is "two hundred sixteen million, seven hundred seventy-two thousand, five hundred eighty-one".