21221111020 has 24 divisors (see below), whose sum is σ = 46909825200. Its totient is φ = 8041684032.

The previous prime is 21221110997. The next prime is 21221111029. The reversal of 21221111020 is 2011112212.

It is not an unprimeable number, because it can be changed into a prime (21221111029) 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, 27922135 + ... + 27922894.

It is an arithmetic number, because the mean of its divisors is an integer number (1954576050).

Almost surely, 2^21221111020 is an apocalyptic number.

21221111020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21221111020 is an abundant number, since it is smaller than the sum of its proper divisors (25688714180).

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

21221111020 is a wasteful number, since it uses less digits than its factorization.

21221111020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55845057 (or 55845055 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21221111020 its reverse (2011112212), we get a palindrome (23232223232).

The spelling of 21221111020 in words is "twenty-one billion, two hundred twenty-one million, one hundred eleven thousand, twenty".