218115217 has 4 divisors (see below), whose sum is σ = 221370736. Its totient is φ = 214859700.

The previous prime is 218115197. The next prime is 218115223. The reversal of 218115217 is 712511812.

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 a cyclic number.

It is not a de Polignac number, because 218115217 - 2⁷ = 218115089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218115277) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1627659 + ... + 1627792.

It is an arithmetic number, because the mean of its divisors is an integer number (55342684).

Almost surely, 2^218115217 is an apocalyptic number.

It is an amenable number.

218115217 is a deficient number, since it is larger than the sum of its proper divisors (3255519).

218115217 is an equidigital number, since it uses as much as digits as its factorization.

218115217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3255518.

The product of its digits is 1120, while the sum is 28.

The square root of 218115217 is about 14768.7242847851. The cubic root of 218115217 is about 601.9521757206.

It can be divided in two parts, 21811 and 5217, that added together give a triangular number (27028 = T₂₃₂).

The spelling of 218115217 in words is "two hundred eighteen million, one hundred fifteen thousand, two hundred seventeen".