20021313121 has 4 divisors (see below), whose sum is σ = 20155684500. Its totient is φ = 19886941744.

The previous prime is 20021313113. The next prime is 20021313157. The reversal of 20021313121 is 12131312002.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12131312002 = 2 ⋅6065656001.

It can be written as a sum of positive squares in 2 ways, for example, as 6188024896 + 13833288225 = 78664^2 + 117615^2 .

It is a cyclic number.

It is not a de Polignac number, because 20021313121 - 2³ = 20021313113 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20021313095 and 20021313104.

It is not an unprimeable number, because it can be changed into a prime (20021310121) 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, 67185466 + ... + 67185763.

It is an arithmetic number, because the mean of its divisors is an integer number (5038921125).

Almost surely, 2^20021313121 is an apocalyptic number.

It is an amenable number.

20021313121 is a deficient number, since it is larger than the sum of its proper divisors (134371379).

20021313121 is a wasteful number, since it uses less digits than its factorization.

20021313121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134371378.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 20021313121 its reverse (12131312002), we get a palindrome (32152625123).

The spelling of 20021313121 in words is "twenty billion, twenty-one million, three hundred thirteen thousand, one hundred twenty-one".