21201010100020 has 12 divisors (see below), whose sum is σ = 44522121210084. Its totient is φ = 8480404040000.

The previous prime is 21201010099987. The next prime is 21201010100051. The reversal of 21201010100020 is 2000101010212.

It can be written as a sum of positive squares in 2 ways, for example, as 2291505667984 + 18909504432036 = 1513772^2 + 4348506^2 .

It is a super-2 number, since 2×21201010100020² (a number of 27 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 530025252481 + ... + 530025252520.

It is an arithmetic number, because the mean of its divisors is an integer number (3710176767507).

Almost surely, 2^{21201010100020} is an apocalyptic number.

21201010100020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21201010100020 is an abundant number, since it is smaller than the sum of its proper divisors (23321111110064).

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

21201010100020 is a wasteful number, since it uses less digits than its factorization.

21201010100020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1060050505010 (or 1060050505008 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21201010100020 its reverse (2000101010212), we get a palindrome (23201111110232).

The spelling of 21201010100020 in words is "twenty-one trillion, two hundred one billion, ten million, one hundred thousand, twenty".