20200120021 has 4 divisors (see below), whose sum is σ = 20200414572. Its totient is φ = 20199825472.

The previous prime is 20200120007. The next prime is 20200120091. The reversal of 20200120021 is 12002100202.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 16406791921 + 3793328100 = 128089^2 + 61590^2 .

It is a cyclic number.

It is not a de Polignac number, because 20200120021 - 2⁷ = 20200119893 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 (20200120091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15741 + ... + 201613.

It is an arithmetic number, because the mean of its divisors is an integer number (5050103643).

Almost surely, 2^20200120021 is an apocalyptic number.

It is an amenable number.

20200120021 is a deficient number, since it is larger than the sum of its proper divisors (294551).

20200120021 is a wasteful number, since it uses less digits than its factorization.

20200120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 294550.

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 20200120021 its reverse (12002100202), we get a palindrome (32202220223).

The spelling of 20200120021 in words is "twenty billion, two hundred million, one hundred twenty thousand, twenty-one".