21340023 has 4 divisors (see below), whose sum is σ = 28453368. Its totient is φ = 14226680.

The previous prime is 21340019. The next prime is 21340051. The reversal of 21340023 is 32004312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21340023 - 2² = 21340019 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21339984 and 21340011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21340003) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3556668 + ... + 3556673.

It is an arithmetic number, because the mean of its divisors is an integer number (7113342).

Almost surely, 2^21340023 is an apocalyptic number.

21340023 is a deficient number, since it is larger than the sum of its proper divisors (7113345).

21340023 is an equidigital number, since it uses as much as digits as its factorization.

21340023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7113344.

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

The square root of 21340023 is about 4619.5262744139. The cubic root of 21340023 is about 277.3734964344.

Adding to 21340023 its reverse (32004312), we get a palindrome (53344335).

The spelling of 21340023 in words is "twenty-one million, three hundred forty thousand, twenty-three".