21001109020 has 48 divisors (see below), whose sum is σ = 45088475040. Its totient is φ = 8213693696.

The previous prime is 21001108993. The next prime is 21001109021. The reversal of 21001109020 is 2090110012.

It is a junction number, because it is equal to n+sod(n) for n = 21001108985 and 21001109003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001109021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 276771 + ... + 344389.

It is an arithmetic number, because the mean of its divisors is an integer number (939343230).

Almost surely, 2^21001109020 is an apocalyptic number.

21001109020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001109020 is an abundant number, since it is smaller than the sum of its proper divisors (24087366020).

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

21001109020 is a wasteful number, since it uses less digits than its factorization.

21001109020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67974 (or 67972 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 16.

Adding to 21001109020 its reverse (2090110012), we get a palindrome (23091219032).

The spelling of 21001109020 in words is "twenty-one billion, one million, one hundred nine thousand, twenty".