18329881 has 2 divisors, whose sum is σ = 18329882. Its totient is φ = 18329880.

The previous prime is 18329879. The next prime is 18329903. The reversal of 18329881 is 18892381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17139600 + 1190281 = 4140^2 + 1091^2 .

It is a cyclic number.

It is not a de Polignac number, because 18329881 - 2¹ = 18329879 is a prime.

It is a super-2 number, since 2×18329881² = 671969074948322, which contains 22 as substring.

Together with 18329879, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18329981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9164940 + 9164941.

It is an arithmetic number, because the mean of its divisors is an integer number (9164941).

Almost surely, 2^18329881 is an apocalyptic number.

It is an amenable number.

18329881 is a deficient number, since it is larger than the sum of its proper divisors (1).

18329881 is an equidigital number, since it uses as much as digits as its factorization.

18329881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27648, while the sum is 40.

The square root of 18329881 is about 4281.3410282294. The cubic root of 18329881 is about 263.6654441708.

Subtracting 18329881 from its reverse (18892381), we obtain a square (562500 = 750²).

The spelling of 18329881 in words is "eighteen million, three hundred twenty-nine thousand, eight hundred eighty-one".