21431223 has 40 divisors (see below), whose sum is σ = 35544960. Its totient is φ = 12759120.

The previous prime is 21431209. The next prime is 21431231. The reversal of 21431223 is 32213412.

It is not a de Polignac number, because 21431223 - 2¹² = 21427127 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21431196 and 21431205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21431023) 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 in 39 ways as a sum of consecutive naturals, for example, 59518 + ... + 59876.

It is an arithmetic number, because the mean of its divisors is an integer number (888624).

Almost surely, 2^21431223 is an apocalyptic number.

21431223 is a deficient number, since it is larger than the sum of its proper divisors (14113737).

21431223 is a wasteful number, since it uses less digits than its factorization.

21431223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 449 (or 440 counting only the distinct ones).

The product of its digits is 288, while the sum is 18.

The square root of 21431223 is about 4629.3868924513. The cubic root of 21431223 is about 277.7680682058.

Adding to 21431223 its reverse (32213412), we get a palindrome (53644635).

The spelling of 21431223 in words is "twenty-one million, four hundred thirty-one thousand, two hundred twenty-three".