21501516017 has 2 divisors, whose sum is σ = 21501516018. Its totient is φ = 21501516016.

The previous prime is 21501515977. The next prime is 21501516019. The reversal of 21501516017 is 71061510512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20713254241 + 788261776 = 143921^2 + 28076^2 .

It is a cyclic number.

It is not a de Polignac number, because 21501516017 - 2⁶ = 21501515953 is a prime.

Together with 21501516019, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21501516019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10750758008 + 10750758009.

It is an arithmetic number, because the mean of its divisors is an integer number (10750758009).

Almost surely, 2^21501516017 is an apocalyptic number.

It is an amenable number.

21501516017 is a deficient number, since it is larger than the sum of its proper divisors (1).

21501516017 is an equidigital number, since it uses as much as digits as its factorization.

21501516017 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2100, while the sum is 29.

The spelling of 21501516017 in words is "twenty-one billion, five hundred one million, five hundred sixteen thousand, seventeen".