21001111122020 has 24 divisors (see below), whose sum is σ = 44162500281144. Its totient is φ = 8388984082176.

The previous prime is 21001111122001. The next prime is 21001111122067. The reversal of 21001111122020 is 2022111110012.

It can be written as a sum of positive squares in 4 ways, for example, as 2429975910244 + 18571135211776 = 1558838^2 + 4309424^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21001111121986 and 21001111122004.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 716257889 + ... + 716287208.

It is an arithmetic number, because the mean of its divisors is an integer number (1840104178381).

Almost surely, 2^{21001111122020} is an apocalyptic number.

21001111122020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001111122020 is an abundant number, since it is smaller than the sum of its proper divisors (23161389159124).

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

21001111122020 is a wasteful number, since it uses less digits than its factorization.

21001111122020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1432545839 (or 1432545837 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21001111122020 its reverse (2022111110012), we get a palindrome (23023222232032).

The spelling of 21001111122020 in words is "twenty-one trillion, one billion, one hundred eleven million, one hundred twenty-two thousand, twenty".