21336564 has 48 divisors (see below), whose sum is σ = 54020736. Its totient is φ = 6528000.

The previous prime is 21336559. The next prime is 21336569. The reversal of 21336564 is 46563312.

It is an interprime number because it is at equal distance from previous prime (21336559) and next prime (21336569).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21336569) 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, 7089 + ... + 9639.

It is an arithmetic number, because the mean of its divisors is an integer number (1125432).

Almost surely, 2^21336564 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21336564, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27010368).

21336564 is an abundant number, since it is smaller than the sum of its proper divisors (32684172).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21336564 is a wasteful number, since it uses less digits than its factorization.

21336564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2616 (or 2614 counting only the distinct ones).

The product of its digits is 12960, while the sum is 30.

The square root of 21336564 is about 4619.1518702030. The cubic root of 21336564 is about 277.3585091533.

Adding to 21336564 its reverse (46563312), we get a palindrome (67899876).

The spelling of 21336564 in words is "twenty-one million, three hundred thirty-six thousand, five hundred sixty-four".