18672581 has 4 divisors (see below), whose sum is σ = 18683532. Its totient is φ = 18661632.

The previous prime is 18672569. The next prime is 18672587. The reversal of 18672581 is 18527681.

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: 18527681 = 389 ⋅47629.

It can be written as a sum of positive squares in 2 ways, for example, as 9424900 + 9247681 = 3070^2 + 3041^2 .

It is a cyclic number.

It is not a de Polignac number, because 18672581 - 2⁶ = 18672517 is a prime.

It is a super-2 number, since 2×18672581² = 697330562403122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18672587) 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, 2306 + ... + 6531.

It is an arithmetic number, because the mean of its divisors is an integer number (4670883).

Almost surely, 2^18672581 is an apocalyptic number.

It is an amenable number.

18672581 is a deficient number, since it is larger than the sum of its proper divisors (10951).

18672581 is an equidigital number, since it uses as much as digits as its factorization.

18672581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10950.

The product of its digits is 26880, while the sum is 38.

The square root of 18672581 is about 4321.1781958165. The cubic root of 18672581 is about 265.2984936046.

The spelling of 18672581 in words is "eighteen million, six hundred seventy-two thousand, five hundred eighty-one".