18217870817 has 4 divisors (see below), whose sum is σ = 18231918276. Its totient is φ = 18203823360.

The previous prime is 18217870807. The next prime is 18217870823. The reversal of 18217870817 is 71807871281.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 71807871281 = 28661 ⋅2505421.

It can be written as a sum of positive squares in 2 ways, for example, as 14736988816 + 3480882001 = 121396^2 + 58999^2 .

It is a cyclic number.

It is not a de Polignac number, because 18217870817 - 2¹² = 18217866721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18217870807) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7021784 + ... + 7024377.

It is an arithmetic number, because the mean of its divisors is an integer number (4557979569).

Almost surely, 2^18217870817 is an apocalyptic number.

It is an amenable number.

18217870817 is a deficient number, since it is larger than the sum of its proper divisors (14047459).

18217870817 is a wasteful number, since it uses less digits than its factorization.

18217870817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14047458.

The product of its (nonzero) digits is 351232, while the sum is 50.

The spelling of 18217870817 in words is "eighteen billion, two hundred seventeen million, eight hundred seventy thousand, eight hundred seventeen".