181649857 has 2 divisors, whose sum is σ = 181649858. Its totient is φ = 181649856.

The previous prime is 181649851. The next prime is 181649893. The reversal of 181649857 is 758946181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 111492481 + 70157376 = 10559^2 + 8376^2 .

It is a cyclic number.

It is not a de Polignac number, because 181649857 - 2⁷ = 181649729 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 181649857.

It is not a weakly prime, because it can be changed into another prime (181649851) 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, 90824928 + 90824929.

It is an arithmetic number, because the mean of its divisors is an integer number (90824929).

Almost surely, 2^181649857 is an apocalyptic number.

It is an amenable number.

181649857 is a deficient number, since it is larger than the sum of its proper divisors (1).

181649857 is an equidigital number, since it uses as much as digits as its factorization.

181649857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 483840, while the sum is 49.

The square root of 181649857 is about 13477.7541526769. The cubic root of 181649857 is about 566.3414565733.

The spelling of 181649857 in words is "one hundred eighty-one million, six hundred forty-nine thousand, eight hundred fifty-seven".