21221220012 has 96 divisors (see below), whose sum is σ = 51596529600. Its totient is φ = 6783160320.

The previous prime is 21221220011. The next prime is 21221220017. The reversal of 21221220012 is 21002212212.

It is a junction number, because it is equal to n+sod(n) for n = 21221219973 and 21221220000.

It is not an unprimeable number, because it can be changed into a prime (21221220011) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 12533838 + ... + 12535530.

It is an arithmetic number, because the mean of its divisors is an integer number (537463850).

Almost surely, 2^21221220012 is an apocalyptic number.

It is an amenable number.

21221220012 is an abundant number, since it is smaller than the sum of its proper divisors (30375309588).

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

21221220012 is a wasteful number, since it uses less digits than its factorization.

21221220012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2163 (or 2161 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21221220012 its reverse (21002212212), we get a palindrome (42223432224).

It can be divided in two parts, 212212200 and 12, that added together give a palindrome (212212212).

The spelling of 21221220012 in words is "twenty-one billion, two hundred twenty-one million, two hundred twenty thousand, twelve".