318129821 has 2 divisors, whose sum is σ = 318129822. Its totient is φ = 318129820.

The previous prime is 318129809. The next prime is 318129841. The reversal of 318129821 is 128921813.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 164121721 + 154008100 = 12811^2 + 12410^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-318129821 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (318129841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159064910 + 159064911.

It is an arithmetic number, because the mean of its divisors is an integer number (159064911).

Almost surely, 2^318129821 is an apocalyptic number.

It is an amenable number.

318129821 is a deficient number, since it is larger than the sum of its proper divisors (1).

318129821 is an equidigital number, since it uses as much as digits as its factorization.

318129821 is an evil number, because the sum of its binary digits is even.

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

The square root of 318129821 is about 17836.1941287933. The cubic root of 318129821 is about 682.6552905995.

The spelling of 318129821 in words is "three hundred eighteen million, one hundred twenty-nine thousand, eight hundred twenty-one".