20431 has 2 divisors, whose sum is σ = 20432.
Its totient is φ = 20430.
The previous prime is 20411. The next prime is 20441. The reversal of 20431 is 13402.
20431 is nontrivially palindromic in base 5.
It is an a-pointer prime, because the next prime (20441) can be obtained adding 20431 to its sum of digits (10).
It is a strong prime.
It is a cyclic number.
It is not a de Polignac number, because 20431 - 25 = 20399 is a prime.
It is a super-2 number, since 2×204312 = 834851522, which contains 22 as substring.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (20411) 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, 10215 + 10216.
It is an arithmetic number, because the mean of its divisors is an integer number (10216).
220431 is an apocalyptic number.
20431 is a deficient number, since it is larger than the sum of its proper divisors (1).
20431 is an equidigital number, since it uses as much as digits as its factorization.
20431 is an odious number, because the sum of its binary digits is odd.
The product of its (nonzero) digits is 24, while the sum is 10.
The square root of 20431 is about 142.9370490811.
The cubic root of 20431 is about 27.3377777161.
Adding to 20431 its reverse (13402), we get a palindrome (33833).
The spelling of 20431 in words is "twenty thousand, four hundred thirty-one".