20121021221 has 4 divisors (see below), whose sum is σ = 22995452832. Its totient is φ = 17246589612.

The previous prime is 20121021199. The next prime is 20121021233. The reversal of 20121021221 is 12212012102.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12212012102 = 2 ⋅6106006051.

It is not a de Polignac number, because 20121021221 - 2⁶ = 20121021157 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20121021196 and 20121021205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20121021521) 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, 1437215795 + ... + 1437215808.

It is an arithmetic number, because the mean of its divisors is an integer number (5748863208).

Almost surely, 2^20121021221 is an apocalyptic number.

It is an amenable number.

20121021221 is a deficient number, since it is larger than the sum of its proper divisors (2874431611).

20121021221 is an equidigital number, since it uses as much as digits as its factorization.

20121021221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2874431610.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 20121021221 its reverse (12212012102), we get a palindrome (32333033323).

It can be divided in two parts, 2012102 and 1221, that multiplied together give a palindrome (2456776542).

The spelling of 20121021221 in words is "twenty billion, one hundred twenty-one million, twenty-one thousand, two hundred twenty-one".