218317493 has 4 divisors (see below), whose sum is σ = 223394688. Its totient is φ = 213240300.

The previous prime is 218317487. The next prime is 218317499. The reversal of 218317493 is 394713812.

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 an interprime number because it is at equal distance from previous prime (218317487) and next prime (218317499).

It is a cyclic number.

It is not a de Polignac number, because 218317493 - 2¹⁸ = 218055349 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 (218317499) 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, 2538533 + ... + 2538618.

It is an arithmetic number, because the mean of its divisors is an integer number (55848672).

Almost surely, 2^218317493 is an apocalyptic number.

It is an amenable number.

218317493 is a deficient number, since it is larger than the sum of its proper divisors (5077195).

218317493 is an equidigital number, since it uses as much as digits as its factorization.

218317493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5077194.

The product of its digits is 36288, while the sum is 38.

The square root of 218317493 is about 14775.5708180767. The cubic root of 218317493 is about 602.1381979827.

The spelling of 218317493 in words is "two hundred eighteen million, three hundred seventeen thousand, four hundred ninety-three".