21013213020 has 96 divisors (see below), whose sum is σ = 62082209280. Its totient is φ = 5295870720.

The previous prime is 21013213019. The next prime is 21013213043. The reversal of 21013213020 is 2031231012.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 458049 + ... + 501831.

It is an arithmetic number, because the mean of its divisors is an integer number (646689680).

Almost surely, 2^21013213020 is an apocalyptic number.

21013213020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21013213020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31041104640).

21013213020 is an abundant number, since it is smaller than the sum of its proper divisors (41068996260).

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

21013213020 is a wasteful number, since it uses less digits than its factorization.

21013213020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44235 (or 44233 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 15.

Adding to 21013213020 its reverse (2031231012), we get a palindrome (23044444032).

The spelling of 21013213020 in words is "twenty-one billion, thirteen million, two hundred thirteen thousand, twenty".