21220212212 has 6 divisors (see below), whose sum is σ = 37135371378. Its totient is φ = 10610106104.

The previous prime is 21220212179. The next prime is 21220212217. The reversal of 21220212212 is 21221202212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 15673537636 + 5546674576 = 125194^2 + 74476^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220212217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2652526523 + ... + 2652526530.

It is an arithmetic number, because the mean of its divisors is an integer number (6189228563).

Almost surely, 2^21220212212 is an apocalyptic number.

It is an amenable number.

21220212212 is a deficient number, since it is larger than the sum of its proper divisors (15915159166).

21220212212 is a wasteful number, since it uses less digits than its factorization.

21220212212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5305053057 (or 5305053055 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21220212212 its reverse (21221202212), we get a palindrome (42441414424).

The spelling of 21220212212 in words is "twenty-one billion, two hundred twenty million, two hundred twelve thousand, two hundred twelve".