21340043 has 4 divisors (see below), whose sum is σ = 21434280. Its totient is φ = 21245808.

The previous prime is 21340019. The next prime is 21340051. The reversal of 21340043 is 34004312.

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 21340043 - 2⁶ = 21339979 is a prime.

It is a Duffinian 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, 46778 + ... + 47231.

It is an arithmetic number, because the mean of its divisors is an integer number (5358570).

Almost surely, 2^21340043 is an apocalyptic number.

21340043 is a deficient number, since it is larger than the sum of its proper divisors (94237).

21340043 is an equidigital number, since it uses as much as digits as its factorization.

21340043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94236.

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 21340043 is about 4619.5284391375. The cubic root of 21340043 is about 277.3735830864.

Adding to 21340043 its reverse (34004312), we get a palindrome (55344355).

The spelling of 21340043 in words is "twenty-one million, three hundred forty thousand, forty-three".