21201021022121 has 4 divisors (see below), whose sum is σ = 21203825026644. Its totient is φ = 21198217017600.

The previous prime is 21201021022081. The next prime is 21201021022127. The reversal of 21201021022121 is 12122012010212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6311455332121 + 14889565690000 = 2512261^2 + 3858700^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21201021022121 is a prime.

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 21201021022121.

It is not an unprimeable number, because it can be changed into a prime (21201021022127) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1401990920 + ... + 1402006041.

It is an arithmetic number, because the mean of its divisors is an integer number (5300956256661).

Almost surely, 2^{21201021022121} is an apocalyptic number.

It is an amenable number.

21201021022121 is a deficient number, since it is larger than the sum of its proper divisors (2804004523).

21201021022121 is an equidigital number, since it uses as much as digits as its factorization.

21201021022121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2804004522.

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

Adding to 21201021022121 its reverse (12122012010212), we get a palindrome (33323033032333).

The spelling of 21201021022121 in words is "twenty-one trillion, two hundred one billion, twenty-one million, twenty-two thousand, one hundred twenty-one".