318781 has 2 divisors, whose sum is σ = 318782. Its totient is φ = 318780.

The previous prime is 318751. The next prime is 318793. The reversal of 318781 is 187813.

It is a happy number.

It is the 231-st star number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 202500 + 116281 = 450^2 + 341^2 .

It is a cyclic number.

It is not a de Polignac number, because 318781 - 2⁵ = 318749 is a prime.

It is a super-2 number, since 2×318781² = 203242651922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (318701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159390 + 159391.

It is an arithmetic number, because the mean of its divisors is an integer number (159391).

2³¹⁸⁷⁸¹ is an apocalyptic number.

318781 is the 253-rd centered decagonal number.

It is an amenable number.

318781 is a deficient number, since it is larger than the sum of its proper divisors (1).

318781 is an equidigital number, since it uses as much as digits as its factorization.

318781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1344, while the sum is 28.

The square root of 318781 is about 564.6069429258. The cubic root of 318781 is about 68.3120748202.

The spelling of 318781 in words is "three hundred eighteen thousand, seven hundred eighty-one".