1091561984 has 40 divisors (see below), whose sum is σ = 2189318208. Its totient is φ = 543697920.

The previous prime is 1091561969. The next prime is 1091562007. The reversal of 1091561984 is 4891651901.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 134819 + ... + 142685.

Almost surely, 2^1091561984 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1091561984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1094659104).

1091561984 is an abundant number, since it is smaller than the sum of its proper divisors (1097756224).

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

1091561984 is an frugal number, since it uses more digits than its factorization.

1091561984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8156 (or 8140 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 44.

The square root of 1091561984 is about 33038.7951354162. The cubic root of 1091561984 is about 1029.6338233970.

The spelling of 1091561984 in words is "one billion, ninety-one million, five hundred sixty-one thousand, nine hundred eighty-four".