21020020000000 has 864 divisors, whose sum is σ = 61951605075360. Its totient is φ = 7096320000000.

The previous prime is 21020019999991. The next prime is 21020020000043. The reversal of 21020020000000 is 2002012.

It is a happy number.

It can be written as a sum of positive squares in 16 ways, for example, as 7651110052096 + 13368909947904 = 2766064^2 + 3656352^2 .

It is a Harshad number since it is a multiple of its sum of digits (7).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 87219999880 + ... + 87220000120.

It is an arithmetic number, because the mean of its divisors is an integer number (71703246615).

Almost surely, 2^{21020020000000} is an apocalyptic number.

21020020000000 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 21020020000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30975802537680).

21020020000000 is an abundant number, since it is smaller than the sum of its proper divisors (40931585075360).

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

21020020000000 is an frugal number, since it uses more digits than its factorization.

21020020000000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 395 (or 344 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 7.

Adding to 21020020000000 its reverse (2002012), we get a palindrome (21020022002012).

The spelling of 21020020000000 in words is "twenty-one trillion, twenty billion, twenty million", and thus it is an aban number and an uban number.