21011121001221 has 8 divisors (see below), whose sum is σ = 30169814771040. Its totient is φ = 12929920616112.

The previous prime is 21011121001201. The next prime is 21011121001243. The reversal of 21011121001221 is 12210012111012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21011121001221 - 2⁷ = 21011121001093 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21011121001221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011121001201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 269373346131 + ... + 269373346208.

It is an arithmetic number, because the mean of its divisors is an integer number (3771226846380).

Almost surely, 2^{21011121001221} is an apocalyptic number.

It is an amenable number.

21011121001221 is a deficient number, since it is larger than the sum of its proper divisors (9158693769819).

21011121001221 is a wasteful number, since it uses less digits than its factorization.

21011121001221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 538746692355.

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 21011121001221 its reverse (12210012111012), we get a palindrome (33221133112233).

The spelling of 21011121001221 in words is "twenty-one trillion, eleven billion, one hundred twenty-one million, one thousand, two hundred twenty-one".