21021210010020 has 192 divisors, whose sum is σ = 64518438297600. Its totient is φ = 5071605273600.

The previous prime is 21021210009931. The next prime is 21021210010037. The reversal of 21021210010020 is 2001001212012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21021210009978 and 21021210010005.

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 63 ways as a sum of consecutive naturals, for example, 507603115 + ... + 507644525.

It is an arithmetic number, because the mean of its divisors is an integer number (336033532800).

Almost surely, 2^{21021210010020} is an apocalyptic number.

21021210010020 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 21021210010020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32259219148800).

21021210010020 is an abundant number, since it is smaller than the sum of its proper divisors (43497228287580).

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

21021210010020 is a wasteful number, since it uses less digits than its factorization.

21021210010020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45106 (or 45104 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21021210010020 its reverse (2001001212012), we get a palindrome (23022211222032).

The spelling of 21021210010020 in words is "twenty-one trillion, twenty-one billion, two hundred ten million, ten thousand, twenty".