12218440 has 32 divisors (see below), whose sum is σ = 29607480. Its totient is φ = 4511232.

The previous prime is 12218417. The next prime is 12218443. The reversal of 12218440 is 4481221.

It can be written as a sum of positive squares in 4 ways, for example, as 9375844 + 2842596 = 3062^2 + 1686^2 .

It is not an unprimeable number, because it can be changed into a prime (12218443) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11229 + ... + 12268.

Almost surely, 2^12218440 is an apocalyptic number.

12218440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

12218440 is an abundant number, since it is smaller than the sum of its proper divisors (17389040).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

12218440 is a wasteful number, since it uses less digits than its factorization.

12218440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23521 (or 23517 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 22.

The square root of 12218440 is about 3495.4885209367. The cubic root of 12218440 is about 230.3236778614.

Adding to 12218440 its reverse (4481221), we get a palindrome (16699661).

The spelling of 12218440 in words is "twelve million, two hundred eighteen thousand, four hundred forty".