21011110020 has 60 divisors (see below), whose sum is σ = 65912635404. Its totient is φ = 5602962240.

The previous prime is 21011110009. The next prime is 21011110039. The reversal of 21011110020 is 2001111012.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 15767322624 + 5243787396 = 125568^2 + 72414^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21011109984 and 21011110011.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 6483291 + ... + 6486530.

Almost surely, 2^21011110020 is an apocalyptic number.

21011110020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21011110020 is an abundant number, since it is smaller than the sum of its proper divisors (44901525384).

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

21011110020 is a wasteful number, since it uses less digits than its factorization.

21011110020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12969842 (or 12969831 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21011110020 its reverse (2001111012), we get a palindrome (23012221032).

The spelling of 21011110020 in words is "twenty-one billion, eleven million, one hundred ten thousand, twenty".