991723 has 2 divisors, whose sum is σ = 991724. Its totient is φ = 991722.

The previous prime is 991717. The next prime is 991733. The reversal of 991723 is 327199.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 991723 - 2¹³ = 983531 is a prime.

It is not a weakly prime, because it can be changed into another prime (991703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495861 + 495862.

It is an arithmetic number, because the mean of its divisors is an integer number (495862).

2⁹⁹¹⁷²³ is an apocalyptic number.

991723 is a deficient number, since it is larger than the sum of its proper divisors (1).

991723 is an equidigital number, since it uses as much as digits as its factorization.

991723 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3402, while the sum is 31.

The square root of 991723 is about 995.8529007840. The cubic root of 991723 is about 99.7233352722.

The spelling of 991723 in words is "nine hundred ninety-one thousand, seven hundred twenty-three".