1218493191 has 4 divisors (see below), whose sum is σ = 1624657592. Its totient is φ = 812328792.

The previous prime is 1218493183. The next prime is 1218493219. The reversal of 1218493191 is 1913948121.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1218493191 - 2³ = 1218493183 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 (1218493091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 203082196 + ... + 203082201.

It is an arithmetic number, because the mean of its divisors is an integer number (406164398).

Almost surely, 2^1218493191 is an apocalyptic number.

1218493191 is a deficient number, since it is larger than the sum of its proper divisors (406164401).

1218493191 is an equidigital number, since it uses as much as digits as its factorization.

1218493191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 406164400.

The product of its digits is 15552, while the sum is 39.

The square root of 1218493191 is about 34906.9218207507. The cubic root of 1218493191 is about 1068.0896390206.

The spelling of 1218493191 in words is "one billion, two hundred eighteen million, four hundred ninety-three thousand, one hundred ninety-one".