1218391438 has 16 divisors (see below), whose sum is σ = 2008955520. Its totient is φ = 549585400.

The previous prime is 1218391409. The next prime is 1218391441. The reversal of 1218391438 is 8341938121.

It is a self number, because there is not a number n which added to its sum of digits gives 1218391438.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 208498 + ... + 214261.

It is an arithmetic number, because the mean of its divisors is an integer number (125559720).

Almost surely, 2^1218391438 is an apocalyptic number.

1218391438 is a deficient number, since it is larger than the sum of its proper divisors (790564082).

1218391438 is a wasteful number, since it uses less digits than its factorization.

1218391438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422903.

The product of its digits is 41472, while the sum is 40.

The square root of 1218391438 is about 34905.4643000204. The cubic root of 1218391438 is about 1068.0599071213.

The spelling of 1218391438 in words is "one billion, two hundred eighteen million, three hundred ninety-one thousand, four hundred thirty-eight".