20001021221121 has 16 divisors (see below), whose sum is σ = 27419274210048. Its totient is φ = 12960791337600.

The previous prime is 20001021221099. The next prime is 20001021221143. The reversal of 20001021221121 is 12112212010002.

It is an interprime number because it is at equal distance from previous prime (20001021221099) and next prime (20001021221143).

It is not a de Polignac number, because 20001021221121 - 2¹⁷ = 20001021090049 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20001021221121.

It is not an unprimeable number, because it can be changed into a prime (20001021221221) 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 15 ways as a sum of consecutive naturals, for example, 299984986 + ... + 300051651.

It is an arithmetic number, because the mean of its divisors is an integer number (1713704638128).

Almost surely, 2^{20001021221121} is an apocalyptic number.

It is an amenable number.

20001021221121 is a deficient number, since it is larger than the sum of its proper divisors (7418252988927).

20001021221121 is a wasteful number, since it uses less digits than its factorization.

20001021221121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 600036952.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 20001021221121 its reverse (12112212010002), we get a palindrome (32113233231123).

It can be divided in two parts, 2000102 and 1221121, that added together give a palindrome (3221223).

The spelling of 20001021221121 in words is "twenty trillion, one billion, twenty-one million, two hundred twenty-one thousand, one hundred twenty-one".