20213123121221 has 8 divisors (see below), whose sum is σ = 20248044284160. Its totient is φ = 20178204770752.

The previous prime is 20213123121209. The next prime is 20213123121239. The reversal of 20213123121221 is 12212132131202.

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

It is a cyclic number.

It is not a de Polignac number, because 20213123121221 - 2¹⁸ = 20213122859077 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20213123121241) 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, 13946540 + ... + 15327498.

It is an arithmetic number, because the mean of its divisors is an integer number (2531005535520).

Almost surely, 2^{20213123121221} is an apocalyptic number.

It is an amenable number.

20213123121221 is a deficient number, since it is larger than the sum of its proper divisors (34921162939).

20213123121221 is a wasteful number, since it uses less digits than its factorization.

20213123121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1406235.

The product of its (nonzero) digits is 576, while the sum is 23.

Adding to 20213123121221 its reverse (12212132131202), we get a palindrome (32425255252423).

The spelling of 20213123121221 in words is "twenty trillion, two hundred thirteen billion, one hundred twenty-three million, one hundred twenty-one thousand, two hundred twenty-one".