21031221012 has 24 divisors (see below), whose sum is σ = 49101780000. Its totient is φ = 7006274016.

The previous prime is 21031220981. The next prime is 21031221019. The reversal of 21031221012 is 21012213012.

It is a junction number, because it is equal to n+sod(n) for n = 21031220982 and 21031221000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031221019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 495387 + ... + 536162.

It is an arithmetic number, because the mean of its divisors is an integer number (2045907500).

Almost surely, 2^21031221012 is an apocalyptic number.

It is an amenable number.

21031221012 is an abundant number, since it is smaller than the sum of its proper divisors (28070558988).

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

21031221012 is a wasteful number, since it uses less digits than its factorization.

21031221012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1033255 (or 1033253 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 15.

Adding to 21031221012 its reverse (21012213012), we get a palindrome (42043434024).

The spelling of 21031221012 in words is "twenty-one billion, thirty-one million, two hundred twenty-one thousand, twelve".