21205552 has 20 divisors (see below), whose sum is σ = 41761216. Its totient is φ = 10428480.

The previous prime is 21205543. The next prime is 21205559. The reversal of 21205552 is 25550212.

It is not an unprimeable number, because it can be changed into a prime (21205559) 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, 9888 + ... + 11839.

Almost surely, 2^21205552 is an apocalyptic number.

It is an amenable number.

21205552 is a deficient number, since it is larger than the sum of its proper divisors (20555664).

21205552 is a wasteful number, since it uses less digits than its factorization.

21205552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21796 (or 21790 counting only the distinct ones).

The product of its (nonzero) digits is 1000, while the sum is 22.

The square root of 21205552 is about 4604.9486424932. The cubic root of 21205552 is about 276.7896590299.

Adding to 21205552 its reverse (25550212), we get a palindrome (46755764).

The spelling of 21205552 in words is "twenty-one million, two hundred five thousand, five hundred fifty-two".