21344539 has 4 divisors (see below), whose sum is σ = 21364056. Its totient is φ = 21325024.

The previous prime is 21344513. The next prime is 21344593. The reversal of 21344539 is 93544312.

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 21344539 - 2⁵ = 21344507 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

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 21344539.

It is not an unprimeable number, because it can be changed into a prime (21344339) 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, 8014 + ... + 10339.

It is an arithmetic number, because the mean of its divisors is an integer number (5341014).

Almost surely, 2^21344539 is an apocalyptic number.

21344539 is a deficient number, since it is larger than the sum of its proper divisors (19517).

21344539 is a wasteful number, since it uses less digits than its factorization.

21344539 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19516.

The product of its digits is 12960, while the sum is 31.

The square root of 21344539 is about 4620.0150432656. The cubic root of 21344539 is about 277.3930610862.

The spelling of 21344539 in words is "twenty-one million, three hundred forty-four thousand, five hundred thirty-nine".