21011121020 has 24 divisors (see below), whose sum is σ = 44132218368. Its totient is φ = 8402760000.

The previous prime is 21011121013. The next prime is 21011121059. The reversal of 21011121020 is 2012111012.

It is a junction number, because it is equal to n+sod(n) for n = 21011120992 and 21011121010.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 956 + ... + 204995.

It is an arithmetic number, because the mean of its divisors is an integer number (1838842432).

Almost surely, 2^21011121020 is an apocalyptic number.

21011121020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21011121020 is an abundant number, since it is smaller than the sum of its proper divisors (23121097348).

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

21011121020 is a wasteful number, since it uses less digits than its factorization.

21011121020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211061 (or 211059 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21011121020 its reverse (2012111012), we get a palindrome (23023232032).

The spelling of 21011121020 in words is "twenty-one billion, eleven million, one hundred twenty-one thousand, twenty".