21000121222001 has 4 divisors (see below), whose sum is σ = 22235422470372. Its totient is φ = 19764819973632.

The previous prime is 21000121221979. The next prime is 21000121222049. The reversal of 21000121222001 is 10022212100012.

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 19610549424400 + 1389571797601 = 4428380^2 + 1178801^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000121222001 - 2¹⁴ = 21000121205617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21000121222601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 617650624160 + ... + 617650624193.

It is an arithmetic number, because the mean of its divisors is an integer number (5558855617593).

Almost surely, 2^{21000121222001} is an apocalyptic number.

It is an amenable number.

21000121222001 is a deficient number, since it is larger than the sum of its proper divisors (1235301248371).

21000121222001 is a wasteful number, since it uses less digits than its factorization.

21000121222001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1235301248370.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21000121222001 its reverse (10022212100012), we get a palindrome (31022333322013).

The spelling of 21000121222001 in words is "twenty-one trillion, one hundred twenty-one million, two hundred twenty-two thousand, one".