21121102020221 has 16 divisors (see below), whose sum is σ = 24332852146176. Its totient is φ = 17958015726336.

The previous prime is 21121102020211. The next prime is 21121102020241. The reversal of 21121102020221 is 12202020112112.

It is a de Polignac number, because none of the positive numbers 2^k-21121102020221 is a prime.

It is a super-2 number, since 2×21121102020221² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21121102020221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121102020211) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2802485 + ... + 7077861.

It is an arithmetic number, because the mean of its divisors is an integer number (1520803259136).

Almost surely, 2^{21121102020221} is an apocalyptic number.

It is an amenable number.

21121102020221 is a deficient number, since it is larger than the sum of its proper divisors (3211750125955).

21121102020221 is a wasteful number, since it uses less digits than its factorization.

21121102020221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4281068.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21121102020221 its reverse (12202020112112), we get a palindrome (33323122132333).

The spelling of 21121102020221 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred two million, twenty thousand, two hundred twenty-one".