21001221220001 has 16 divisors (see below), whose sum is σ = 23703628959360. Its totient is φ = 18431191739520.

The previous prime is 21001221219971. The next prime is 21001221220033. The reversal of 21001221220001 is 10002212210012.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001221220001 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21001281220001) 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, 2057405 + ... + 6799658.

It is an arithmetic number, because the mean of its divisors is an integer number (1481476809960).

Almost surely, 2^{21001221220001} is an apocalyptic number.

It is an amenable number.

21001221220001 is a deficient number, since it is larger than the sum of its proper divisors (2702407739359).

21001221220001 is a wasteful number, since it uses less digits than its factorization.

21001221220001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8864536.

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

Adding to 21001221220001 its reverse (10002212210012), we get a palindrome (31003433430013).

The spelling of 21001221220001 in words is "twenty-one trillion, one billion, two hundred twenty-one million, two hundred twenty thousand, one".