18681431 has 2 divisors, whose sum is σ = 18681432. Its totient is φ = 18681430.

The previous prime is 18681373. The next prime is 18681463. The reversal of 18681431 is 13418681.

It is a happy number.

It is an a-pointer prime, because the next prime (18681463) can be obtained adding 18681431 to its sum of digits (32).

It is a strong prime.

It is an emirp because it is prime and its reverse (13418681) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18681431 - 2²² = 14487127 is a prime.

It is a super-2 number, since 2×18681431² = 697991728415522, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18681491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9340715 + 9340716.

It is an arithmetic number, because the mean of its divisors is an integer number (9340716).

Almost surely, 2^18681431 is an apocalyptic number.

18681431 is a deficient number, since it is larger than the sum of its proper divisors (1).

18681431 is an equidigital number, since it uses as much as digits as its factorization.

18681431 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4608, while the sum is 32.

The square root of 18681431 is about 4322.2021007815. The cubic root of 18681431 is about 265.3404003418.

The spelling of 18681431 in words is "eighteen million, six hundred eighty-one thousand, four hundred thirty-one".