18618881 has 4 divisors (see below), whose sum is σ = 19122132. Its totient is φ = 18115632.

The previous prime is 18618877. The next prime is 18618923. The reversal of 18618881 is 18881681.

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 17505856 + 1113025 = 4184^2 + 1055^2 .

It is a cyclic number.

It is not a de Polignac number, because 18618881 - 2² = 18618877 is a prime.

It is a super-3 number, since 3×18618881³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18618811) 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, 251570 + ... + 251643.

It is an arithmetic number, because the mean of its divisors is an integer number (4780533).

Almost surely, 2^18618881 is an apocalyptic number.

It is an amenable number.

18618881 is a deficient number, since it is larger than the sum of its proper divisors (503251).

18618881 is an equidigital number, since it uses as much as digits as its factorization.

18618881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 503250.

The product of its digits is 24576, while the sum is 41.

The square root of 18618881 is about 4314.9601388657. The cubic root of 18618881 is about 265.0439276889.

The spelling of 18618881 in words is "eighteen million, six hundred eighteen thousand, eight hundred eighty-one".