1091123021 has 4 divisors (see below), whose sum is σ = 1091193312. Its totient is φ = 1091052732.

The previous prime is 1091123017. The next prime is 1091123029. The reversal of 1091123021 is 1203211901.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1091123021 - 2² = 1091123017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1091122984 and 1091123002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1091123029) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 431 + ... + 46716.

It is an arithmetic number, because the mean of its divisors is an integer number (272798328).

Almost surely, 2^1091123021 is an apocalyptic number.

It is an amenable number.

1091123021 is a deficient number, since it is larger than the sum of its proper divisors (70291).

1091123021 is an equidigital number, since it uses as much as digits as its factorization.

1091123021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70290.

The product of its (nonzero) digits is 108, while the sum is 20.

The square root of 1091123021 is about 33032.1513226129. The cubic root of 1091123021 is about 1029.4957851980.

Adding to 1091123021 its reverse (1203211901), we get a palindrome (2294334922).

The spelling of 1091123021 in words is "one billion, ninety-one million, one hundred twenty-three thousand, twenty-one".