21013020100 has 36 divisors (see below), whose sum is σ = 47170613700. Its totient is φ = 8115372160.

The previous prime is 21013020089. The next prime is 21013020121. The reversal of 21013020100 is 102031012.

It can be written as a sum of positive squares in 6 ways, for example, as 3985901956 + 17027118144 = 63134^2 + 130488^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3620035 + ... + 3625834.

It is an arithmetic number, because the mean of its divisors is an integer number (1310294825).

Almost surely, 2^21013020100 is an apocalyptic number.

21013020100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21013020100 is an abundant number, since it is smaller than the sum of its proper divisors (26157593600).

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

21013020100 is a wasteful number, since it uses less digits than its factorization.

21013020100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7245912 (or 7245905 counting only the distinct ones).

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

Adding to 21013020100 its reverse (102031012), we get a palindrome (21115051112).

The spelling of 21013020100 in words is "twenty-one billion, thirteen million, twenty thousand, one hundred".