21020111020 has 12 divisors (see below), whose sum is σ = 44142233184. Its totient is φ = 8408044400.

The previous prime is 21020111017. The next prime is 21020111059. The reversal of 21020111020 is 2011102012.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 21020110988 and 21020111006.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 525502756 + ... + 525502795.

It is an arithmetic number, because the mean of its divisors is an integer number (3678519432).

Almost surely, 2^21020111020 is an apocalyptic number.

21020111020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21020111020 is an abundant number, since it is smaller than the sum of its proper divisors (23122122164).

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

21020111020 is a wasteful number, since it uses less digits than its factorization.

21020111020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1051005560 (or 1051005558 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21020111020 its reverse (2011102012), we get a palindrome (23031213032).

The spelling of 21020111020 in words is "twenty-one billion, twenty million, one hundred eleven thousand, twenty".