991144 has 32 divisors (see below), whose sum is σ = 2318400. Its totient is φ = 385920.

The previous prime is 991129. The next prime is 991147. The reversal of 991144 is 441199.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a zygodrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (991147) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 189 + ... + 1420.

It is an arithmetic number, because the mean of its divisors is an integer number (72450).

2⁹⁹¹¹⁴⁴ is an apocalyptic number.

It is an amenable number.

991144 is an abundant number, since it is smaller than the sum of its proper divisors (1327256).

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

991144 is a wasteful number, since it uses less digits than its factorization.

991144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1633 (or 1629 counting only the distinct ones).

The product of its digits is 1296, while the sum is 28.

The square root of 991144 is about 995.5621527559. The cubic root of 991144 is about 99.7039242567.

Subtracting from 991144 its reverse (441199), we obtain a palindrome (549945).

The spelling of 991144 in words is "nine hundred ninety-one thousand, one hundred forty-four".