18681857 has 2 divisors, whose sum is σ = 18681858. Its totient is φ = 18681856.

The previous prime is 18681853. The next prime is 18681863. The reversal of 18681857 is 75818681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18671041 + 10816 = 4321^2 + 104^2 .

It is a cyclic number.

It is not a de Polignac number, because 18681857 - 2² = 18681853 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18681851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9340928 + 9340929.

It is an arithmetic number, because the mean of its divisors is an integer number (9340929).

Almost surely, 2^18681857 is an apocalyptic number.

It is an amenable number.

18681857 is a deficient number, since it is larger than the sum of its proper divisors (1).

18681857 is an equidigital number, since it uses as much as digits as its factorization.

18681857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 107520, while the sum is 44.

The square root of 18681857 is about 4322.2513809356. The cubic root of 18681857 is about 265.3424172135.

The spelling of 18681857 in words is "eighteen million, six hundred eighty-one thousand, eight hundred fifty-seven".