21205264 has 40 divisors (see below), whose sum is σ = 44372160. Its totient is φ = 9787008.

The previous prime is 21205243. The next prime is 21205279. The reversal of 21205264 is 46250212.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9679 + ... + 11665.

It is an arithmetic number, because the mean of its divisors is an integer number (1109304).

Almost surely, 2^21205264 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 21205264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22186080).

21205264 is an abundant number, since it is smaller than the sum of its proper divisors (23166896).

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

21205264 is a wasteful number, since it uses less digits than its factorization.

21205264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2047 (or 2041 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 21205264 is about 4604.9173716800. The cubic root of 21205264 is about 276.7884059652.

Adding to 21205264 its reverse (46250212), we get a palindrome (67455476).

The spelling of 21205264 in words is "twenty-one million, two hundred five thousand, two hundred sixty-four".