991423 has 8 divisors (see below), whose sum is σ = 1086480. Its totient is φ = 900480.

The previous prime is 991409. The next prime is 991427. The reversal of 991423 is 324199.

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 not a de Polignac number, because 991423 - 2¹⁷ = 860351 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 991391 and 991400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991427) 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, 513 + ... + 1498.

It is an arithmetic number, because the mean of its divisors is an integer number (135810).

2⁹⁹¹⁴²³ is an apocalyptic number.

991423 is a deficient number, since it is larger than the sum of its proper divisors (95057).

991423 is a wasteful number, since it uses less digits than its factorization.

991423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2057.

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

The square root of 991423 is about 995.7022647358. The cubic root of 991423 is about 99.7132786946.

The spelling of 991423 in words is "nine hundred ninety-one thousand, four hundred twenty-three".