20231021221 has 4 divisors (see below), whose sum is σ = 20508158572. Its totient is φ = 19953883872.

The previous prime is 20231021219. The next prime is 20231021233. The reversal of 20231021221 is 12212013202.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12212013202 = 2 ⋅6106006601.

It can be written as a sum of positive squares in 2 ways, for example, as 17559165121 + 2671856100 = 132511^2 + 51690^2 .

It is a cyclic number.

It is not a de Polignac number, because 20231021221 - 2¹ = 20231021219 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20231021195 and 20231021204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20231021521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 138568566 + ... + 138568711.

It is an arithmetic number, because the mean of its divisors is an integer number (5127039643).

Almost surely, 2^20231021221 is an apocalyptic number.

It is an amenable number.

20231021221 is a deficient number, since it is larger than the sum of its proper divisors (277137351).

20231021221 is an equidigital number, since it uses as much as digits as its factorization.

20231021221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277137350.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 20231021221 its reverse (12212013202), we get a palindrome (32443034423).

The spelling of 20231021221 in words is "twenty billion, two hundred thirty-one million, twenty-one thousand, two hundred twenty-one".