21021012010020 has 192 divisors, whose sum is σ = 65713410846720. Its totient is φ = 4978035532800.

The previous prime is 21021012009887. The next prime is 21021012010051. The reversal of 21021012010020 is 2001021012012.

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 = 21021012009978 and 21021012010005.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2719605 + ... + 7031235.

It is an arithmetic number, because the mean of its divisors is an integer number (342257348160).

Almost surely, 2^{21021012010020} is an apocalyptic number.

21021012010020 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 21021012010020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32856705423360).

21021012010020 is an abundant number, since it is smaller than the sum of its proper divisors (44692398836700).

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

21021012010020 is a wasteful number, since it uses less digits than its factorization.

21021012010020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4311826 (or 4311824 counting only the distinct ones).

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

Adding to 21021012010020 its reverse (2001021012012), we get a palindrome (23022033022032).

The spelling of 21021012010020 in words is "twenty-one trillion, twenty-one billion, twelve million, ten thousand, twenty".