21202232121221 has 4 divisors (see below), whose sum is σ = 21270406501344. Its totient is φ = 21134057741100.

The previous prime is 21202232121179. The next prime is 21202232121227. The reversal of 21202232121221 is 12212123220212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21202232121221 - 2²² = 21202227926917 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 (21202232121227) 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, 34087189595 + ... + 34087190216.

It is an arithmetic number, because the mean of its divisors is an integer number (5317601625336).

Almost surely, 2^{21202232121221} is an apocalyptic number.

It is an amenable number.

21202232121221 is a deficient number, since it is larger than the sum of its proper divisors (68174380123).

21202232121221 is an equidigital number, since it uses as much as digits as its factorization.

21202232121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68174380122.

The product of its (nonzero) digits is 768, while the sum is 23.

Adding to 21202232121221 its reverse (12212123220212), we get a palindrome (33414355341433).

The spelling of 21202232121221 in words is "twenty-one trillion, two hundred two billion, two hundred thirty-two million, one hundred twenty-one thousand, two hundred twenty-one".