21221201212 has 12 divisors (see below), whose sum is σ = 37153188016. Its totient is φ = 10606004640.

The previous prime is 21221201191. The next prime is 21221201231. The reversal of 21221201212 is 21210212212.

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, 1138593 + ... + 1157080.

Almost surely, 2^21221201212 is an apocalyptic number.

It is an amenable number.

21221201212 is a deficient number, since it is larger than the sum of its proper divisors (15931986804).

21221201212 is a wasteful number, since it uses less digits than its factorization.

21221201212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2297988 (or 2297986 counting only the distinct ones).

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

Adding to 21221201212 its reverse (21210212212), we get a palindrome (42431413424).

The spelling of 21221201212 in words is "twenty-one billion, two hundred twenty-one million, two hundred one thousand, two hundred twelve".