991623 has 8 divisors (see below), whose sum is σ = 1353088. Its totient is φ = 645624.

The previous prime is 991621. The next prime is 991633. The reversal of 991623 is 326199.

991623 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 991623 - 2¹ = 991621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991623.

It is not an unprimeable number, because it can be changed into a prime (991621) 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, 3715 + ... + 3972.

It is an arithmetic number, because the mean of its divisors is an integer number (169136).

2⁹⁹¹⁶²³ is an apocalyptic number.

991623 is a deficient number, since it is larger than the sum of its proper divisors (361465).

991623 is a wasteful number, since it uses less digits than its factorization.

991623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7733.

The product of its digits is 2916, while the sum is 30.

The square root of 991623 is about 995.8026912998. The cubic root of 991623 is about 99.7199833050.

The spelling of 991623 in words is "nine hundred ninety-one thousand, six hundred twenty-three".