20121121121021 has 4 divisors (see below), whose sum is σ = 20121139937052. Its totient is φ = 20121102304992.

The previous prime is 20121121120999. The next prime is 20121121121039. The reversal of 20121121121021 is 12012112112102.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13151785118521 + 6969336002500 = 3626539^2 + 2639950^2 .

It is a cyclic number.

It is not a de Polignac number, because 20121121121021 - 2¹⁰ = 20121121119997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20121121121041) 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, 7700696 + ... + 9977121.

It is an arithmetic number, because the mean of its divisors is an integer number (5030284984263).

Almost surely, 2^{20121121121021} is an apocalyptic number.

It is an amenable number.

20121121121021 is a deficient number, since it is larger than the sum of its proper divisors (18816031).

20121121121021 is a wasteful number, since it uses less digits than its factorization.

20121121121021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18816030.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 20121121121021 its reverse (12012112112102), we get a palindrome (32133233233123).

The spelling of 20121121121021 in words is "twenty trillion, one hundred twenty-one billion, one hundred twenty-one million, one hundred twenty-one thousand, twenty-one".