1591891812 has 144 divisors (see below), whose sum is σ = 4820430720. Its totient is φ = 454307616.

The previous prime is 1591891799. The next prime is 1591891813. The reversal of 1591891812 is 2181981951.

It is a super-2 number, since 2×1591891812² = 5068239082225286688, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1591891813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1814718 + ... + 1815594.

Almost surely, 2^1591891812 is an apocalyptic number.

1591891812 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1591891812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2410215360).

1591891812 is an abundant number, since it is smaller than the sum of its proper divisors (3228538908).

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

1591891812 is an frugal number, since it uses more digits than its factorization.

1591891812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 925 (or 889 counting only the distinct ones).

The product of its digits is 51840, while the sum is 45.

The square root of 1591891812 is about 39898.5189198797. The cubic root of 1591891812 is about 1167.6280413534.

The spelling of 1591891812 in words is "one billion, five hundred ninety-one million, eight hundred ninety-one thousand, eight hundred twelve".