18366881 has 4 divisors (see below), whose sum is σ = 19779732. Its totient is φ = 16954032.

The previous prime is 18366869. The next prime is 18366899. The reversal of 18366881 is 18866381.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11560000 + 6806881 = 3400^2 + 2609^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18366881 is a prime.

It is a super-2 number, since 2×18366881² = 674684635336322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18356881) 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, 706406 + ... + 706431.

It is an arithmetic number, because the mean of its divisors is an integer number (4944933).

Almost surely, 2^18366881 is an apocalyptic number.

It is an amenable number.

18366881 is a deficient number, since it is larger than the sum of its proper divisors (1412851).

18366881 is a wasteful number, since it uses less digits than its factorization.

18366881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1412850.

The product of its digits is 55296, while the sum is 41.

The square root of 18366881 is about 4285.6599258457. The cubic root of 18366881 is about 263.8427332774.

Subtracting 18366881 from its reverse (18866381), we obtain a triangular number (499500 = T₉₉₉).

The spelling of 18366881 in words is "eighteen million, three hundred sixty-six thousand, eight hundred eighty-one".