21304023 has 16 divisors (see below), whose sum is σ = 30782976. Its totient is φ = 13027680.

The previous prime is 21304001. The next prime is 21304027. The reversal of 21304023 is 32040312.

It is not a de Polignac number, because 21304023 - 2⁹ = 21303511 is a prime.

It is a super-2 number, since 2×21304023² = 907722791969058, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21303993 and 21304011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21304027) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4878 + ... + 8148.

It is an arithmetic number, because the mean of its divisors is an integer number (1923936).

Almost surely, 2^21304023 is an apocalyptic number.

21304023 is a deficient number, since it is larger than the sum of its proper divisors (9478953).

21304023 is a wasteful number, since it uses less digits than its factorization.

21304023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3454.

The product of its (nonzero) digits is 144, while the sum is 15.

The square root of 21304023 is about 4615.6281262684. The cubic root of 21304023 is about 277.2174349626.

Adding to 21304023 its reverse (32040312), we get a palindrome (53344335).

The spelling of 21304023 in words is "twenty-one million, three hundred four thousand, twenty-three".