21221220212212 has 6 divisors (see below), whose sum is σ = 37137135371378. Its totient is φ = 10610610106104.

The previous prime is 21221220212189. The next prime is 21221220212249. The reversal of 21221220212212 is 21221202212212.

It can be written as a sum of positive squares in only one way, i.e., 19401241139856 + 1819979072356 = 4404684^2 + 1349066^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2652652526523 + ... + 2652652526530.

Almost surely, 2^{21221220212212} is an apocalyptic number.

It is an amenable number.

21221220212212 is a deficient number, since it is larger than the sum of its proper divisors (15915915159166).

21221220212212 is a wasteful number, since it uses less digits than its factorization.

21221220212212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5305305053057 (or 5305305053055 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 22.

Adding to 21221220212212 its reverse (21221202212212), we get a palindrome (42442422424424).

The spelling of 21221220212212 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twenty million, two hundred twelve thousand, two hundred twelve".