21210111201220 has 24 divisors (see below), whose sum is σ = 44546795256600. Its totient is φ = 8482985102592.

The previous prime is 21210111201131. The next prime is 21210111201239. The reversal of 21210111201220 is 2210211101212.

It can be written as a sum of positive squares in 4 ways, for example, as 4703962375044 + 16506148826176 = 2168862^2 + 4062776^2 .

It is a super-2 number, since 2×21210111201220² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21210111201194 and 21210111201203.

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, 66046935 + ... + 66367294.

It is an arithmetic number, because the mean of its divisors is an integer number (1856116469025).

Almost surely, 2^{21210111201220} is an apocalyptic number.

21210111201220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21210111201220 is an abundant number, since it is smaller than the sum of its proper divisors (23336684055380).

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

21210111201220 is a wasteful number, since it uses less digits than its factorization.

21210111201220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132422247 (or 132422245 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21210111201220 its reverse (2210211101212), we get a palindrome (23420322302432).

The spelling of 21210111201220 in words is "twenty-one trillion, two hundred ten billion, one hundred eleven million, two hundred one thousand, two hundred twenty".