21205330 has 32 divisors (see below), whose sum is σ = 40435200. Its totient is φ = 7984512.

The previous prime is 21205313. The next prime is 21205361. The reversal of 21205330 is 3350212.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44031 + ... + 44509.

It is an arithmetic number, because the mean of its divisors is an integer number (1263600).

Almost surely, 2^21205330 is an apocalyptic number.

21205330 is a deficient number, since it is larger than the sum of its proper divisors (19229870).

21205330 is a wasteful number, since it uses less digits than its factorization.

21205330 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 738.

The product of its (nonzero) digits is 180, while the sum is 16.

The square root of 21205330 is about 4604.9245379268. The cubic root of 21205330 is about 276.7886931269.

Adding to 21205330 its reverse (3350212), we get a palindrome (24555542).

The spelling of 21205330 in words is "twenty-one million, two hundred five thousand, three hundred thirty".