21343021 has 4 divisors (see below), whose sum is σ = 24392032. Its totient is φ = 18294012.

The previous prime is 21343019. The next prime is 21343039. The reversal of 21343021 is 12034312.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21343021 - 2¹ = 21343019 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21342986 and 21343004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21344021) 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 3 ways as a sum of consecutive naturals, for example, 1524495 + ... + 1524508.

It is an arithmetic number, because the mean of its divisors is an integer number (6098008).

Almost surely, 2^21343021 is an apocalyptic number.

It is an amenable number.

21343021 is a deficient number, since it is larger than the sum of its proper divisors (3049011).

21343021 is an equidigital number, since it uses as much as digits as its factorization.

21343021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3049010.

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

The square root of 21343021 is about 4619.8507551651. The cubic root of 21343021 is about 277.3864849678.

Adding to 21343021 its reverse (12034312), we get a palindrome (33377333).

It can be divided in two parts, 213 and 43021, that added together give a palindrome (43234).

The spelling of 21343021 in words is "twenty-one million, three hundred forty-three thousand, twenty-one".