21331023 has 12 divisors (see below), whose sum is σ = 33085080. Its totient is φ = 12189072.

The previous prime is 21331021. The next prime is 21331043. The reversal of 21331023 is 32013312.

It is not a de Polignac number, because 21331023 - 2¹ = 21331021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21330993 and 21331011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21331021) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 72408 + ... + 72701.

It is an arithmetic number, because the mean of its divisors is an integer number (2757090).

Almost surely, 2^21331023 is an apocalyptic number.

21331023 is a deficient number, since it is larger than the sum of its proper divisors (11754057).

21331023 is a wasteful number, since it uses less digits than its factorization.

21331023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145126 (or 145119 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 15.

The square root of 21331023 is about 4618.5520458256. The cubic root of 21331023 is about 277.3344975309.

Adding to 21331023 its reverse (32013312), we get a palindrome (53344335).

The spelling of 21331023 in words is "twenty-one million, three hundred thirty-one thousand, twenty-three".