18139481 has 2 divisors, whose sum is σ = 18139482. Its totient is φ = 18139480.

The previous prime is 18139463. The next prime is 18139483. The reversal of 18139481 is 18493181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18139081 + 400 = 4259^2 + 20^2 .

It is a cyclic number.

It is not a de Polignac number, because 18139481 - 2⁶ = 18139417 is a prime.

It is a super-2 number, since 2×18139481² = 658081541898722, which contains 22 as substring.

Together with 18139483, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18139483) 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, 9069740 + 9069741.

It is an arithmetic number, because the mean of its divisors is an integer number (9069741).

Almost surely, 2^18139481 is an apocalyptic number.

It is an amenable number.

18139481 is a deficient number, since it is larger than the sum of its proper divisors (1).

18139481 is an equidigital number, since it uses as much as digits as its factorization.

18139481 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6912, while the sum is 35.

The square root of 18139481 is about 4259.0469591213. The cubic root of 18139481 is about 262.7493310539.

The spelling of 18139481 in words is "eighteen million, one hundred thirty-nine thousand, four hundred eighty-one".