21101001020 has 48 divisors (see below), whose sum is σ = 48398515200. Its totient is φ = 7663878720.

The previous prime is 21101001017. The next prime is 21101001037. The reversal of 21101001020 is 2010010112.

It is a junction number, because it is equal to n+sod(n) for n = 21101000989 and 21101001007.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 127421 + ... + 241739.

It is an arithmetic number, because the mean of its divisors is an integer number (1008302400).

Almost surely, 2^21101001020 is an apocalyptic number.

21101001020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21101001020 is an abundant number, since it is smaller than the sum of its proper divisors (27297514180).

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

21101001020 is a wasteful number, since it uses less digits than its factorization.

21101001020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115178 (or 115176 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 21101001020 its reverse (2010010112), we get a palindrome (23111011132).

The spelling of 21101001020 in words is "twenty-one billion, one hundred one million, one thousand, twenty".