1091208021 has 16 divisors (see below), whose sum is σ = 1526169600. Its totient is φ = 692191280.

The previous prime is 1091208011. The next prime is 1091208023. The reversal of 1091208021 is 1208021901.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1091208021 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1091207982 and 1091208000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1091208023) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 28221 + ... + 54578.

It is an arithmetic number, because the mean of its divisors is an integer number (95385600).

Almost surely, 2^1091208021 is an apocalyptic number.

It is an amenable number.

1091208021 is a deficient number, since it is larger than the sum of its proper divisors (434961579).

1091208021 is a wasteful number, since it uses less digits than its factorization.

1091208021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83016.

The product of its (nonzero) digits is 288, while the sum is 24.

The square root of 1091208021 is about 33033.4379228079. The cubic root of 1091208021 is about 1029.5225175547.

Adding to 1091208021 its reverse (1208021901), we get a palindrome (2299229922).

The spelling of 1091208021 in words is "one billion, ninety-one million, two hundred eight thousand, twenty-one".