18617892217 has 4 divisors (see below), whose sum is σ = 18618170740. Its totient is φ = 18617613696.

The previous prime is 18617892211. The next prime is 18617892283. The reversal of 18617892217 is 71229871681.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 71229871681 = 161977 ⋅439753.

It can be written as a sum of positive squares in 2 ways, for example, as 7000501561 + 11617390656 = 83669^2 + 107784^2 .

It is a 3-Lehmer number, since φ(18617892217) divides (18617892217-1)³.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18617892217 is a prime.

It is a deceptive number, since it divides R_18617892216.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18617892211) 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, 27853 + ... + 194965.

It is an arithmetic number, because the mean of its divisors is an integer number (4654542685).

Almost surely, 2^18617892217 is an apocalyptic number.

18617892217 is the 111409-th pentagonal number.

It is an amenable number.

18617892217 is a deficient number, since it is larger than the sum of its proper divisors (278523).

18617892217 is a wasteful number, since it uses less digits than its factorization.

18617892217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 278522.

The product of its digits is 677376, while the sum is 52.

The spelling of 18617892217 in words is "eighteen billion, six hundred seventeen million, eight hundred ninety-two thousand, two hundred seventeen".