1091788020 has 36 divisors (see below), whose sum is σ = 3311757540. Its totient is φ = 291143424.

The previous prime is 1091787997. The next prime is 1091788037. The reversal of 1091788020 is 208871901.

It can be written as a sum of positive squares in 2 ways, for example, as 179506404 + 912281616 = 13398^2 + 30204^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3032565 + ... + 3032924.

It is an arithmetic number, because the mean of its divisors is an integer number (91993265).

Almost surely, 2^1091788020 is an apocalyptic number.

1091788020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1091788020 is an abundant number, since it is smaller than the sum of its proper divisors (2219969520).

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

1091788020 is a wasteful number, since it uses less digits than its factorization.

1091788020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6065504 (or 6065499 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 1091788020 is about 33042.2157247361. The cubic root of 1091788020 is about 1029.7048892187.

The spelling of 1091788020 in words is "one billion, ninety-one million, seven hundred eighty-eight thousand, twenty".