21340423 has 16 divisors (see below), whose sum is σ = 24748416. Its totient is φ = 18224640.

The previous prime is 21340421. The next prime is 21340441. The reversal of 21340423 is 32404312.

It is a cyclic number.

It is not a de Polignac number, because 21340423 - 2¹ = 21340421 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21340423.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21340421) 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, 12690 + ... + 14272.

It is an arithmetic number, because the mean of its divisors is an integer number (1546776).

Almost surely, 2^21340423 is an apocalyptic number.

21340423 is a deficient number, since it is larger than the sum of its proper divisors (3407993).

21340423 is a wasteful number, since it uses less digits than its factorization.

21340423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1674.

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 21340423 is about 4619.5695686936. The cubic root of 21340423 is about 277.3752294645.

Adding to 21340423 its reverse (32404312), we get a palindrome (53744735).

The spelling of 21340423 in words is "twenty-one million, three hundred forty thousand, four hundred twenty-three".