18518881 has 2 divisors, whose sum is σ = 18518882. Its totient is φ = 18518880.

The previous prime is 18518879. The next prime is 18518917. The reversal of 18518881 is 18881581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10137856 + 8381025 = 3184^2 + 2895^2 .

It is a cyclic number.

It is not a de Polignac number, because 18518881 - 2¹ = 18518879 is a prime.

It is a super-2 number, since 2×18518881² = 685897906984322, which contains 22 as substring.

Together with 18518879, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18518821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9259440 + 9259441.

It is an arithmetic number, because the mean of its divisors is an integer number (9259441).

Almost surely, 2^18518881 is an apocalyptic number.

It is an amenable number.

18518881 is a deficient number, since it is larger than the sum of its proper divisors (1).

18518881 is an equidigital number, since it uses as much as digits as its factorization.

18518881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20480, while the sum is 40.

The square root of 18518881 is about 4303.3569454555. The cubic root of 18518881 is about 264.5685681939.

The spelling of 18518881 in words is "eighteen million, five hundred eighteen thousand, eight hundred eighty-one".