18128561 has 8 divisors (see below), whose sum is σ = 19813248. Its totient is φ = 16450000.

The previous prime is 18128549. The next prime is 18128563. The reversal of 18128561 is 16582181.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18128561 - 2¹⁸ = 17866417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18128563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6536 + ... + 8886.

It is an arithmetic number, because the mean of its divisors is an integer number (2476656).

Almost surely, 2^18128561 is an apocalyptic number.

18128561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18128561 is a deficient number, since it is larger than the sum of its proper divisors (1684687).

18128561 is a wasteful number, since it uses less digits than its factorization.

18128561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3063.

The product of its digits is 3840, while the sum is 32.

The square root of 18128561 is about 4257.7647891822. The cubic root of 18128561 is about 262.6965952811.

The spelling of 18128561 in words is "eighteen million, one hundred twenty-eight thousand, five hundred sixty-one".