18617783817889 has 3 divisors (see below), whose sum is σ = 18617788132723. Its totient is φ = 18617779503056.

The previous prime is 18617783817883. The next prime is 18617783817901. The reversal of 18617783817889 is 98871838771681.

The square root of 18617783817889 is 4314833.

It is a perfect power (a square), and thus also a powerful number.

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.

It can be written as a sum of positive squares in only one way, i.e., 434313950625 + 18183469867264 = 659025^2 + 4264208^2 .

It is not a de Polignac number, because 18617783817889 - 2⁷ = 18617783817761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18617783817883) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2157417 + ... + 6472249.

Almost surely, 2^{18617783817889} is an apocalyptic number.

18617783817889 is the 4314833-rd square number.

18617783817889 is the 2157417-th centered octagonal number.

It is an amenable number.

18617783817889 is a deficient number, since it is larger than the sum of its proper divisors (4314834).

18617783817889 is an frugal number, since it uses more digits than its factorization.

18617783817889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8629666 (or 4314833 counting only the distinct ones).

The product of its digits is 1820786688, while the sum is 82.

The spelling of 18617783817889 in words is "eighteen trillion, six hundred seventeen billion, seven hundred eighty-three million, eight hundred seventeen thousand, eight hundred eighty-nine".