21431023 has 2 divisors, whose sum is σ = 21431024. Its totient is φ = 21431022.

The previous prime is 21431017. The next prime is 21431057. The reversal of 21431023 is 32013412.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21431023 - 2⁵ = 21430991 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21430988 and 21431006.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21431063) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10715511 + 10715512.

It is an arithmetic number, because the mean of its divisors is an integer number (10715512).

Almost surely, 2^21431023 is an apocalyptic number.

21431023 is a deficient number, since it is larger than the sum of its proper divisors (1).

21431023 is an equidigital number, since it uses as much as digits as its factorization.

21431023 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 21431023 is about 4629.3652912683. The cubic root of 21431023 is about 277.7672041427.

Adding to 21431023 its reverse (32013412), we get a palindrome (53444435).

The spelling of 21431023 in words is "twenty-one million, four hundred thirty-one thousand, twenty-three".