991110222021 has 4 divisors (see below), whose sum is σ = 1321480296032. Its totient is φ = 660740148012.

The previous prime is 991110222017. The next prime is 991110222041. The reversal of 991110222021 is 120222011199.

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 an emirpimes, since its reverse is a distinct semiprime: 120222011199 = 3 ⋅40074003733.

It is not a de Polignac number, because 991110222021 - 2² = 991110222017 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 991110222021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991110222041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 165185037001 + ... + 165185037006.

It is an arithmetic number, because the mean of its divisors is an integer number (330370074008).

Almost surely, 2^991110222021 is an apocalyptic number.

It is an amenable number.

991110222021 is a deficient number, since it is larger than the sum of its proper divisors (330370074011).

991110222021 is a wasteful number, since it uses less digits than its factorization.

991110222021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330370074010.

The product of its (nonzero) digits is 1296, while the sum is 30.

The spelling of 991110222021 in words is "nine hundred ninety-one billion, one hundred ten million, two hundred twenty-two thousand, twenty-one".