21795874018417 has 2 divisors, whose sum is σ = 21795874018418. Its totient is φ = 21795874018416.

The previous prime is 21795874018351. The next prime is 21795874018421. The reversal of 21795874018417 is 71481047859712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21539335820401 + 256538198016 = 4641049^2 + 506496^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21795874018417 is a prime.

It is not a weakly prime, because it can be changed into another prime (21795874028417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10897937009208 + 10897937009209.

It is an arithmetic number, because the mean of its divisors is an integer number (10897937009209).

Almost surely, 2^{21795874018417} is an apocalyptic number.

It is an amenable number.

21795874018417 is a deficient number, since it is larger than the sum of its proper divisors (1).

21795874018417 is an equidigital number, since it uses as much as digits as its factorization.

21795874018417 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 31610880, while the sum is 64.

The spelling of 21795874018417 in words is "twenty-one trillion, seven hundred ninety-five billion, eight hundred seventy-four million, eighteen thousand, four hundred seventeen".