21012121220221 has 8 divisors (see below), whose sum is σ = 21017470604480. Its totient is φ = 21006772149888.

The previous prime is 21012121220219. The next prime is 21012121220267. The reversal of 21012121220221 is 12202212121012.

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 21012121220221 - 2¹ = 21012121220219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012121220201) 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, 190757800 + ... + 190867918.

It is an arithmetic number, because the mean of its divisors is an integer number (2627183825560).

Almost surely, 2^{21012121220221} is an apocalyptic number.

It is an amenable number.

21012121220221 is a deficient number, since it is larger than the sum of its proper divisors (5349384259).

21012121220221 is a wasteful number, since it uses less digits than its factorization.

21012121220221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156963.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21012121220221 its reverse (12202212121012), we get a palindrome (33214333341233).

The spelling of 21012121220221 in words is "twenty-one trillion, twelve billion, one hundred twenty-one million, two hundred twenty thousand, two hundred twenty-one".