1091891772 has 96 divisors (see below), whose sum is σ = 3008275200. Its totient is φ = 341516736.

The previous prime is 1091891761. The next prime is 1091891821. The reversal of 1091891772 is 2771981901.

It is a happy number.

It is a super-2 number, since 2×1091891772² = 2384455283522599968, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 217078 + ... + 222050.

It is an arithmetic number, because the mean of its divisors is an integer number (31336200).

Almost surely, 2^1091891772 is an apocalyptic number.

1091891772 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 1091891772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1504137600).

1091891772 is an abundant number, since it is smaller than the sum of its proper divisors (1916383428).

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

1091891772 is a wasteful number, since it uses less digits than its factorization.

1091891772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5112 (or 5104 counting only the distinct ones).

The product of its (nonzero) digits is 63504, while the sum is 45.

The square root of 1091891772 is about 33043.7856790048. The cubic root of 1091891772 is about 1029.7375056106.

The spelling of 1091891772 in words is "one billion, ninety-one million, eight hundred ninety-one thousand, seven hundred seventy-two".