21000121012221 has 48 divisors (see below), whose sum is σ = 33718026619200. Its totient is φ = 11522809792512.

The previous prime is 21000121012219. The next prime is 21000121012231. The reversal of 21000121012221 is 12221012100012.

It is not a de Polignac number, because 21000121012221 - 2¹ = 21000121012219 is a prime.

It is a super-6 number, since 6×21000121012221⁶ (a number of 81 digits) contains 666666 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21000121012221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000121012231) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 48817416 + ... + 49245713.

It is an arithmetic number, because the mean of its divisors is an integer number (702458887900).

Almost surely, 2^{21000121012221} is an apocalyptic number.

It is an amenable number.

21000121012221 is a deficient number, since it is larger than the sum of its proper divisors (12717905606979).

21000121012221 is a wasteful number, since it uses less digits than its factorization.

21000121012221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98063198 (or 98063181 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21000121012221 its reverse (12221012100012), we get a palindrome (33221133112233).

The spelling of 21000121012221 in words is "twenty-one trillion, one hundred twenty-one million, twelve thousand, two hundred twenty-one".