1221804918 has 64 divisors (see below), whose sum is σ = 2863872000. Its totient is φ = 385044192.

The previous prime is 1221804889. The next prime is 1221804931. The reversal of 1221804918 is 8194081221.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 693723 + ... + 695481.

It is an arithmetic number, because the mean of its divisors is an integer number (44748000).

Almost surely, 2^1221804918 is an apocalyptic number.

1221804918 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221804918, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1431936000).

1221804918 is an abundant number, since it is smaller than the sum of its proper divisors (1642067082).

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

1221804918 is a wasteful number, since it uses less digits than its factorization.

1221804918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2466 (or 2460 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 36.

The square root of 1221804918 is about 34954.3261700179. The cubic root of 1221804918 is about 1069.0564127273.

The spelling of 1221804918 in words is "one billion, two hundred twenty-one million, eight hundred four thousand, nine hundred eighteen".