21011220012 has 24 divisors (see below), whose sum is σ = 50716738800. Its totient is φ = 6762231616.

The previous prime is 21011219987. The next prime is 21011220019. The reversal of 21011220012 is 21002211012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a self number, because there is not a number n which added to its sum of digits gives 21011220012.

It is not an unprimeable number, because it can be changed into a prime (21011220019) 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 7 ways as a sum of consecutive naturals, for example, 30188187 + ... + 30188882.

It is an arithmetic number, because the mean of its divisors is an integer number (2113197450).

Almost surely, 2^21011220012 is an apocalyptic number.

It is an amenable number.

21011220012 is an abundant number, since it is smaller than the sum of its proper divisors (29705518788).

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

21011220012 is a wasteful number, since it uses less digits than its factorization.

21011220012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60377105 (or 60377103 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21011220012 its reverse (21002211012), we get a palindrome (42013431024).

The spelling of 21011220012 in words is "twenty-one billion, eleven million, two hundred twenty thousand, twelve".