21122020001221 has 4 divisors (see below), whose sum is σ = 21126007550412. Its totient is φ = 21118032452032.

The previous prime is 21122020001197. The next prime is 21122020001227. The reversal of 21122020001221 is 12210002022112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7961370128100 + 13160649873121 = 2821590^2 + 3627761^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122020001221 - 2¹¹ = 21122019999173 is a prime.

It is a super-2 number, since 2×21122020001221² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21122020001195 and 21122020001204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122020001227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1993766650 + ... + 1993777243.

It is an arithmetic number, because the mean of its divisors is an integer number (5281501887603).

Almost surely, 2^{21122020001221} is an apocalyptic number.

It is an amenable number.

21122020001221 is a deficient number, since it is larger than the sum of its proper divisors (3987549191).

21122020001221 is an equidigital number, since it uses as much as digits as its factorization.

21122020001221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3987549190.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21122020001221 its reverse (12210002022112), we get a palindrome (33332022023333).

The spelling of 21122020001221 in words is "twenty-one trillion, one hundred twenty-two billion, twenty million, one thousand, two hundred twenty-one".