20200121 has 2 divisors, whose sum is σ = 20200122. Its totient is φ = 20200120.

The previous prime is 20200111. The next prime is 20200123. The reversal of 20200121 is 12100202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19044496 + 1155625 = 4364^2 + 1075^2 .

It is a cyclic number.

It is not a de Polignac number, because 20200121 - 2⁶ = 20200057 is a prime.

Together with 20200123, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 20200099 and 20200108.

It is not a weakly prime, because it can be changed into another prime (20200123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10100060 + 10100061.

It is an arithmetic number, because the mean of its divisors is an integer number (10100061).

Almost surely, 2^20200121 is an apocalyptic number.

It is an amenable number.

20200121 is a deficient number, since it is larger than the sum of its proper divisors (1).

20200121 is an equidigital number, since it uses as much as digits as its factorization.

20200121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8, while the sum is 8.

The square root of 20200121 is about 4494.4544719020. The cubic root of 20200121 is about 272.3441119441.

Adding to 20200121 its reverse (12100202), we get a palindrome (32300323).

The spelling of 20200121 in words is "twenty million, two hundred thousand, one hundred twenty-one".