21201200121221 has 32 divisors (see below), whose sum is σ = 23700347798400. Its totient is φ = 18879232619520.

The previous prime is 21201200121209. The next prime is 21201200121229. The reversal of 21201200121221 is 12212100210212.

It is a de Polignac number, because none of the positive numbers 2^k-21201200121221 is a prime.

It is a super-2 number, since 2×21201200121221² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21201200121221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201200121229) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9545201 + ... + 11554793.

It is an arithmetic number, because the mean of its divisors is an integer number (740635868700).

Almost surely, 2^{21201200121221} is an apocalyptic number.

It is an amenable number.

21201200121221 is a deficient number, since it is larger than the sum of its proper divisors (2499147677179).

21201200121221 is a wasteful number, since it uses less digits than its factorization.

21201200121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2010149.

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

Adding to 21201200121221 its reverse (12212100210212), we get a palindrome (33413300331433).

The spelling of 21201200121221 in words is "twenty-one trillion, two hundred one billion, two hundred million, one hundred twenty-one thousand, two hundred twenty-one".