21201221212 has 12 divisors (see below), whose sum is σ = 39054881320. Its totient is φ = 10042683696.

The previous prime is 21201221207. The next prime is 21201221287. The reversal of 21201221212 is 21212210212.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139481643 + ... + 139481794.

Almost surely, 2^21201221212 is an apocalyptic number.

It is an amenable number.

21201221212 is a deficient number, since it is larger than the sum of its proper divisors (17853660108).

21201221212 is a wasteful number, since it uses less digits than its factorization.

21201221212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 278963460 (or 278963458 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21201221212 its reverse (21212210212), we get a palindrome (42413431424).

The spelling of 21201221212 in words is "twenty-one billion, two hundred one million, two hundred twenty-one thousand, two hundred twelve".