20521988017 has 2 divisors, whose sum is σ = 20521988018. Its totient is φ = 20521988016.

The previous prime is 20521987999. The next prime is 20521988033. The reversal of 20521988017 is 71088912502.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16082297856 + 4439690161 = 126816^2 + 66631^2 .

It is a cyclic number.

It is not a de Polignac number, because 20521988017 - 2¹⁵ = 20521955249 is a prime.

It is not a weakly prime, because it can be changed into another prime (20521988087) 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 as a sum of consecutive naturals, namely, 10260994008 + 10260994009.

It is an arithmetic number, because the mean of its divisors is an integer number (10260994009).

Almost surely, 2^20521988017 is an apocalyptic number.

It is an amenable number.

20521988017 is a deficient number, since it is larger than the sum of its proper divisors (1).

20521988017 is an equidigital number, since it uses as much as digits as its factorization.

20521988017 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 80640, while the sum is 43.

The spelling of 20521988017 in words is "twenty billion, five hundred twenty-one million, nine hundred eighty-eight thousand, seventeen".