423991 has 2 divisors, whose sum is σ = 423992. Its totient is φ = 423990.

The previous prime is 423989. The next prime is 424001. The reversal of 423991 is 199324.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 423991 - 2¹ = 423989 is a prime.

Together with 423989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (423931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 211995 + 211996.

It is an arithmetic number, because the mean of its divisors is an integer number (211996).

2⁴²³⁹⁹¹ is an apocalyptic number.

423991 is a deficient number, since it is larger than the sum of its proper divisors (1).

423991 is an equidigital number, since it uses as much as digits as its factorization.

423991 is an odious number, because the sum of its binary digits is odd.

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

The square root of 423991 is about 651.1459129873. The cubic root of 423991 is about 75.1251835308.

The spelling of 423991 in words is "four hundred twenty-three thousand, nine hundred ninety-one".