20001331221 has 4 divisors (see below), whose sum is σ = 26668441632. Its totient is φ = 13334220812.

The previous prime is 20001331211. The next prime is 20001331243. The reversal of 20001331221 is 12213310002.

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 20001331221 - 2³⁴ = 2821462037 is a prime.

It is a super-2 number, since 2×20001331221² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20001331221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20001331211) 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, 3333555201 + ... + 3333555206.

It is an arithmetic number, because the mean of its divisors is an integer number (6667110408).

Almost surely, 2^20001331221 is an apocalyptic number.

It is an amenable number.

20001331221 is a deficient number, since it is larger than the sum of its proper divisors (6667110411).

20001331221 is an equidigital number, since it uses as much as digits as its factorization.

20001331221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6667110410.

The product of its (nonzero) digits is 72, while the sum is 15.

Adding to 20001331221 its reverse (12213310002), we get a palindrome (32214641223).

The spelling of 20001331221 in words is "twenty billion, one million, three hundred thirty-one thousand, two hundred twenty-one".