318689821 has 2 divisors, whose sum is σ = 318689822. Its totient is φ = 318689820.

The previous prime is 318689807. The next prime is 318689923. The reversal of 318689821 is 128986813.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 192127321 + 126562500 = 13861^2 + 11250^2 .

It is an emirp because it is prime and its reverse (128986813) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 318689821 - 2⁹ = 318689309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (318681821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159344910 + 159344911.

It is an arithmetic number, because the mean of its divisors is an integer number (159344911).

Almost surely, 2^318689821 is an apocalyptic number.

It is an amenable number.

318689821 is a deficient number, since it is larger than the sum of its proper divisors (1).

318689821 is an equidigital number, since it uses as much as digits as its factorization.

318689821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 165888, while the sum is 46.

The square root of 318689821 is about 17851.8856426989. The cubic root of 318689821 is about 683.0556123601.

The spelling of 318689821 in words is "three hundred eighteen million, six hundred eighty-nine thousand, eight hundred twenty-one".