21336481 has 4 divisors (see below), whose sum is σ = 21400132. Its totient is φ = 21272832.

The previous prime is 21336473. The next prime is 21336503. The reversal of 21336481 is 18463312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12390400 + 8946081 = 3520^2 + 2991^2 .

It is a cyclic number.

It is not a de Polignac number, because 21336481 - 2³ = 21336473 is a prime.

It is a super-2 number, since 2×21336481² = 910490842926722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21336181) 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, 31320 + ... + 31993.

It is an arithmetic number, because the mean of its divisors is an integer number (5350033).

Almost surely, 2^21336481 is an apocalyptic number.

It is an amenable number.

21336481 is a deficient number, since it is larger than the sum of its proper divisors (63651).

21336481 is an equidigital number, since it uses as much as digits as its factorization.

21336481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63650.

The product of its digits is 3456, while the sum is 28.

The square root of 21336481 is about 4619.1428858610. The cubic root of 21336481 is about 277.3581495080.

Adding to 21336481 its reverse (18463312), we get a palindrome (39799793).

The spelling of 21336481 in words is "twenty-one million, three hundred thirty-six thousand, four hundred eighty-one".