991022 has 4 divisors (see below), whose sum is σ = 1486536. Its totient is φ = 495510.

The previous prime is 991009. The next prime is 991027. The reversal of 991022 is 220199.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991027) by changing a digit.

991022 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 as a sum of consecutive naturals, namely, 247754 + ... + 247757.

It is an arithmetic number, because the mean of its divisors is an integer number (371634).

2⁹⁹¹⁰²² is an apocalyptic number.

991022 is a deficient number, since it is larger than the sum of its proper divisors (495514).

991022 is a wasteful number, since it uses less digits than its factorization.

991022 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 495513.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 991022 is about 995.5008789549. The cubic root of 991022 is about 99.6998332340.

The spelling of 991022 in words is "nine hundred ninety-one thousand, twenty-two".