18798561 has 10 divisors (see below), whose sum is σ = 28081922. Its totient is φ = 12532320.

The previous prime is 18798557. The next prime is 18798569. The reversal of 18798561 is 16589781.

18798561 is a `hidden beast` number, since 1 + 87 + 9 + 8 + 561 = 666.

It can be written as a sum of positive squares in only one way, i.e., 18662400 + 136161 = 4320^2 + 369^2 .

It is not a de Polignac number, because 18798561 - 2² = 18798557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18798569) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 115960 + ... + 116121.

Almost surely, 2^18798561 is an apocalyptic number.

It is an amenable number.

18798561 is a deficient number, since it is larger than the sum of its proper divisors (9283361).

18798561 is an equidigital number, since it uses as much as digits as its factorization.

18798561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232093 (or 232084 counting only the distinct ones).

The product of its digits is 120960, while the sum is 45.

The square root of 18798561 is about 4335.7307342592. The cubic root of 18798561 is about 265.8937946374.

It can be divided in two parts, 1879 and 8561, that added together give a triangular number (10440 = T₁₄₄).

The spelling of 18798561 in words is "eighteen million, seven hundred ninety-eight thousand, five hundred sixty-one".