21002220040121 has 4 divisors (see below), whose sum is σ = 21002721364212. Its totient is φ = 21001718716032.

The previous prime is 21002220040069. The next prime is 21002220040129. The reversal of 21002220040121 is 12104002220012.

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 8614600684096 + 12387619356025 = 2935064^2 + 3519605^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002220040121 - 2⁴² = 16604173529017 is a prime.

It is a super-2 number, since 2×21002220040121² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21002220040121.

It is not an unprimeable number, because it can be changed into a prime (21002220040129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 250599200 + ... + 250682993.

It is an arithmetic number, because the mean of its divisors is an integer number (5250680341053).

Almost surely, 2^{21002220040121} is an apocalyptic number.

It is an amenable number.

21002220040121 is a deficient number, since it is larger than the sum of its proper divisors (501324091).

21002220040121 is an equidigital number, since it uses as much as digits as its factorization.

21002220040121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 501324090.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21002220040121 its reverse (12104002220012), we get a palindrome (33106222260133).

The spelling of 21002220040121 in words is "twenty-one trillion, two billion, two hundred twenty million, forty thousand, one hundred twenty-one".