21718522017 has 6 divisors (see below), whose sum is σ = 31371198482. Its totient is φ = 14479014672.

The previous prime is 21718522013. The next prime is 21718522027. The reversal of 21718522017 is 71022581712.

It can be written as a sum of positive squares in only one way, i.e., 11656225296 + 10062296721 = 107964^2 + 100311^2 .

It is not a de Polignac number, because 21718522017 - 2² = 21718522013 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21718522013) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1206584548 + ... + 1206584565.

Almost surely, 2^21718522017 is an apocalyptic number.

It is an amenable number.

21718522017 is a deficient number, since it is larger than the sum of its proper divisors (9652676465).

21718522017 is a wasteful number, since it uses less digits than its factorization.

21718522017 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2413169119 (or 2413169116 counting only the distinct ones).

The product of its (nonzero) digits is 15680, while the sum is 36.

The spelling of 21718522017 in words is "twenty-one billion, seven hundred eighteen million, five hundred twenty-two thousand, seventeen".