21201221210 has 16 divisors (see below), whose sum is σ = 41097752136. Its totient is φ = 7828143168.

The previous prime is 21201221207. The next prime is 21201221287. The reversal of 21201221210 is 1212210212.

It can be written as a sum of positive squares in 4 ways, for example, as 15895409929 + 5305811281 = 126077^2 + 72841^2 .

It is a Curzon number.

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, 81543029 + ... + 81543288.

Almost surely, 2^21201221210 is an apocalyptic number.

21201221210 is a deficient number, since it is larger than the sum of its proper divisors (19896530926).

21201221210 is a wasteful number, since it uses less digits than its factorization.

21201221210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163086337.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21201221210 its reverse (1212210212), we get a palindrome (22413431422).

The spelling of 21201221210 in words is "twenty-one billion, two hundred one million, two hundred twenty-one thousand, two hundred ten".