1891438218 has 12 divisors (see below), whose sum is σ = 4098116178. Its totient is φ = 630479400.

The previous prime is 1891438217. The next prime is 1891438253. The reversal of 1891438218 is 8128341981.

It can be written as a sum of positive squares in only one way, i.e., 1236436569 + 655001649 = 35163^2 + 25593^2 .

It is a super-2 number, since 2×1891438218² = 7155077065022031048, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1891438217) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 52539933 + ... + 52539968.

Almost surely, 2^1891438218 is an apocalyptic number.

1891438218 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1891438218 is an abundant number, since it is smaller than the sum of its proper divisors (2206677960).

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

1891438218 is a wasteful number, since it uses less digits than its factorization.

1891438218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105079909 (or 105079906 counting only the distinct ones).

The product of its digits is 110592, while the sum is 45.

The square root of 1891438218 is about 43490.6681714595. The cubic root of 1891438218 is about 1236.6991245379.

The spelling of 1891438218 in words is "one billion, eight hundred ninety-one million, four hundred thirty-eight thousand, two hundred eighteen".