21798634817 has 2 divisors, whose sum is σ = 21798634818. Its totient is φ = 21798634816.

The previous prime is 21798634801. The next prime is 21798634843. The reversal of 21798634817 is 71843689712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19222158736 + 2576476081 = 138644^2 + 50759^2 .

It is a cyclic number.

It is not a de Polignac number, because 21798634817 - 2⁴ = 21798634801 is a prime.

It is not a weakly prime, because it can be changed into another prime (21791634817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10899317408 + 10899317409.

It is an arithmetic number, because the mean of its divisors is an integer number (10899317409).

Almost surely, 2^21798634817 is an apocalyptic number.

It is an amenable number.

21798634817 is a deficient number, since it is larger than the sum of its proper divisors (1).

21798634817 is an equidigital number, since it uses as much as digits as its factorization.

21798634817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4064256, while the sum is 56.

The spelling of 21798634817 in words is "twenty-one billion, seven hundred ninety-eight million, six hundred thirty-four thousand, eight hundred seventeen".