20420203121 has 4 divisors (see below), whose sum is σ = 20420570100. Its totient is φ = 20419836144.

The previous prime is 20420203079. The next prime is 20420203163. The reversal of 20420203121 is 12130202402.

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

It is an interprime number because it is at equal distance from previous prime (20420203079) and next prime (20420203163).

It can be written as a sum of positive squares in 2 ways, for example, as 16239934096 + 4180269025 = 127436^2 + 64655^2 .

It is a cyclic number.

It is not a de Polignac number, because 20420203121 - 2¹⁸ = 20419940977 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20420203121.

It is not an unprimeable number, because it can be changed into a prime (20420203721) 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, 80906 + ... + 217683.

It is an arithmetic number, because the mean of its divisors is an integer number (5105142525).

Almost surely, 2^20420203121 is an apocalyptic number.

It is an amenable number.

20420203121 is a deficient number, since it is larger than the sum of its proper divisors (366979).

20420203121 is an equidigital number, since it uses as much as digits as its factorization.

20420203121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366978.

The product of its (nonzero) digits is 192, while the sum is 17.

Adding to 20420203121 its reverse (12130202402), we get a palindrome (32550405523).

The spelling of 20420203121 in words is "twenty billion, four hundred twenty million, two hundred three thousand, one hundred twenty-one".