21100013020 has 24 divisors (see below), whose sum is σ = 44748744768. Its totient is φ = 8356440000.

The previous prime is 21100013003. The next prime is 21100013021. The reversal of 21100013020 is 2031000112.

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 = 21100012988 and 21100013006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100013021) 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, 5220756 + ... + 5224795.

It is an arithmetic number, because the mean of its divisors is an integer number (1864531032).

Almost surely, 2^21100013020 is an apocalyptic number.

21100013020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21100013020 is an abundant number, since it is smaller than the sum of its proper divisors (23648731748).

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

21100013020 is a wasteful number, since it uses less digits than its factorization.

21100013020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10445661 (or 10445659 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 10.

Adding to 21100013020 its reverse (2031000112), we get a palindrome (23131013132).

The spelling of 21100013020 in words is "twenty-one billion, one hundred million, thirteen thousand, twenty".