21021110020 has 48 divisors (see below), whose sum is σ = 45171157248. Its totient is φ = 8213553920.

The previous prime is 21021109979. The next prime is 21021110029. The reversal of 21021110020 is 2001112012.

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 = 21021109979 and 21021110006.

It is not an unprimeable number, because it can be changed into a prime (21021110029) 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 15 ways as a sum of consecutive naturals, for example, 468279 + ... + 511201.

It is an arithmetic number, because the mean of its divisors is an integer number (941065776).

Almost surely, 2^21021110020 is an apocalyptic number.

21021110020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021110020 is an abundant number, since it is smaller than the sum of its proper divisors (24150047228).

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

21021110020 is a wasteful number, since it uses less digits than its factorization.

21021110020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43500 (or 43498 counting only the distinct ones).

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

Adding to 21021110020 its reverse (2001112012), we get a palindrome (23022222032).

The spelling of 21021110020 in words is "twenty-one billion, twenty-one million, one hundred ten thousand, twenty".