16818581 has 12 divisors (see below), whose sum is σ = 18444972. Its totient is φ = 15243648.

The previous prime is 16818563. The next prime is 16818623. The reversal of 16818581 is 18581861.

It can be written as a sum of positive squares in 2 ways, for example, as 1144900 + 15673681 = 1070^2 + 3959^2 .

It is not a de Polignac number, because 16818581 - 2⁶ = 16818517 is a prime.

It is a super-2 number, since 2×16818581² = 565729333707122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16818511) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 148781 + ... + 148893.

It is an arithmetic number, because the mean of its divisors is an integer number (1537081).

Almost surely, 2^16818581 is an apocalyptic number.

It is an amenable number.

16818581 is a deficient number, since it is larger than the sum of its proper divisors (1626391).

16818581 is a wasteful number, since it uses less digits than its factorization.

16818581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340 (or 233 counting only the distinct ones).

The product of its digits is 15360, while the sum is 38.

The square root of 16818581 is about 4101.0463299017. The cubic root of 16818581 is about 256.2102205949.

The spelling of 16818581 in words is "sixteen million, eight hundred eighteen thousand, five hundred eighty-one".