21000220011121 has 4 divisors (see below), whose sum is σ = 22615621550452. Its totient is φ = 19384818471792.

The previous prime is 21000220011077. The next prime is 21000220011131. The reversal of 21000220011121 is 12111002200012.

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 12493291122225 + 8506928888896 = 3534585^2 + 2916664^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000220011121 - 2⁴¹ = 18801196755569 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (13), and also a Moran number because the ratio is a prime number: 1615401539317 = 21000220011121 / (2 + 1 + 0 + 0 + 0 + 2 + 2 + 0 + 0 + 1 + 1 + 1 + 2 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21000220011131) 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, 807700769646 + ... + 807700769671.

It is an arithmetic number, because the mean of its divisors is an integer number (5653905387613).

Almost surely, 2^{21000220011121} is an apocalyptic number.

It is an amenable number.

21000220011121 is a deficient number, since it is larger than the sum of its proper divisors (1615401539331).

21000220011121 is a wasteful number, since it uses less digits than its factorization.

21000220011121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1615401539330.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21000220011121 its reverse (12111002200012), we get a palindrome (33111222211133).

The spelling of 21000220011121 in words is "twenty-one trillion, two hundred twenty million, eleven thousand, one hundred twenty-one".