18491689 has 6 divisors (see below), whose sum is σ = 18635694. Its totient is φ = 18348480.

The previous prime is 18491687. The next prime is 18491713. The reversal of 18491689 is 98619481.

It can be written as a sum of positive squares in 3 ways, for example, as 514089 + 17977600 = 717^2 + 4240^2 .

It is not a de Polignac number, because 18491689 - 2¹ = 18491687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18491687) 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, 66619 + ... + 66895.

It is an arithmetic number, because the mean of its divisors is an integer number (3105949).

Almost surely, 2^18491689 is an apocalyptic number.

It is an amenable number.

18491689 is a deficient number, since it is larger than the sum of its proper divisors (144005).

18491689 is an frugal number, since it uses more digits than its factorization.

18491689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 795 (or 518 counting only the distinct ones).

The product of its digits is 124416, while the sum is 46.

The square root of 18491689 is about 4300.1963908640. The cubic root of 18491689 is about 264.4390126242.

The spelling of 18491689 in words is "eighteen million, four hundred ninety-one thousand, six hundred eighty-nine".