21221111212 has 24 divisors (see below), whose sum is σ = 42862448160. Its totient is φ = 9004713600.

The previous prime is 21221111173. The next prime is 21221111273. The reversal of 21221111212 is 21211112212.

It is a super-2 number, since 2×21221111212² (a number of 21 digits) contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3749137 + ... + 3754792.

It is an arithmetic number, because the mean of its divisors is an integer number (1785935340).

Almost surely, 2^21221111212 is an apocalyptic number.

It is an amenable number.

21221111212 is an abundant number, since it is smaller than the sum of its proper divisors (21641336948).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21221111212 is a wasteful number, since it uses less digits than its factorization.

21221111212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7504041 (or 7504039 counting only the distinct ones).

The product of its digits is 32, while the sum is 16.

Adding to 21221111212 its reverse (21211112212), we get a palindrome (42432223424).

The spelling of 21221111212 in words is "twenty-one billion, two hundred twenty-one million, one hundred eleven thousand, two hundred twelve".