991243 has 8 divisors (see below), whose sum is σ = 1093680. Its totient is φ = 890880.

The previous prime is 991229. The next prime is 991261. The reversal of 991243 is 342199.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991223) 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, 603 + ... + 1531.

It is an arithmetic number, because the mean of its divisors is an integer number (136710).

2⁹⁹¹²⁴³ is an apocalyptic number.

991243 is a deficient number, since it is larger than the sum of its proper divisors (102437).

991243 is a wasteful number, since it uses less digits than its factorization.

991243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1037.

The product of its digits is 1944, while the sum is 28.

The square root of 991243 is about 995.6118721671. The cubic root of 991243 is about 99.7072437743.

The spelling of 991243 in words is "nine hundred ninety-one thousand, two hundred forty-three".