21020121020 has 24 divisors (see below), whose sum is σ = 45566199168. Its totient is φ = 8136820800.

The previous prime is 21020121007. The next prime is 21020121029. The reversal of 21020121020 is 2012102012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21020120992 and 21020121010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020121029) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16951091 + ... + 16952330.

It is an arithmetic number, because the mean of its divisors is an integer number (1898591632).

Almost surely, 2^21020121020 is an apocalyptic number.

21020121020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21020121020 is an abundant number, since it is smaller than the sum of its proper divisors (24546078148).

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

21020121020 is a wasteful number, since it uses less digits than its factorization.

21020121020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33903461 (or 33903459 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21020121020 its reverse (2012102012), we get a palindrome (23032223032).

The spelling of 21020121020 in words is "twenty-one billion, twenty million, one hundred twenty-one thousand, twenty".