21313423 has 6 divisors (see below), whose sum is σ = 21822504. Its totient is φ = 20815956.

The previous prime is 21313379. The next prime is 21313429. The reversal of 21313423 is 32431312.

It is not a de Polignac number, because 21313423 - 2⁹ = 21312911 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 21313423.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21313429) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3915 + ... + 7612.

It is an arithmetic number, because the mean of its divisors is an integer number (3637084).

Almost surely, 2^21313423 is an apocalyptic number.

21313423 is a deficient number, since it is larger than the sum of its proper divisors (509081).

21313423 is an equidigital number, since it uses as much as digits as its factorization.

21313423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11613 (or 11570 counting only the distinct ones).

The product of its digits is 432, while the sum is 19.

The square root of 21313423 is about 4616.6462935772. The cubic root of 21313423 is about 277.2582012961.

Adding to 21313423 its reverse (32431312), we get a palindrome (53744735).

It can be divided in two parts, 21313 and 423, that added together give a triangular number (21736 = T₂₀₈).

The spelling of 21313423 in words is "twenty-one million, three hundred thirteen thousand, four hundred twenty-three".