21202021221221 has 4 divisors (see below), whose sum is σ = 21202106746272. Its totient is φ = 21201935696172.

The previous prime is 21202021221203. The next prime is 21202021221301. The reversal of 21202021221221 is 12212212020212.

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 a de Polignac number, because none of the positive numbers 2^k-21202021221221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21202021221193 and 21202021221202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202221221221) 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, 42389585 + ... + 42886838.

It is an arithmetic number, because the mean of its divisors is an integer number (5300526686568).

Almost surely, 2^{21202021221221} is an apocalyptic number.

It is an amenable number.

21202021221221 is a deficient number, since it is larger than the sum of its proper divisors (85525051).

21202021221221 is an equidigital number, since it uses as much as digits as its factorization.

21202021221221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85525050.

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21202021221221 its reverse (12212212020212), we get a palindrome (33414233241433).

The spelling of 21202021221221 in words is "twenty-one trillion, two hundred two billion, twenty-one million, two hundred twenty-one thousand, two hundred twenty-one".