515681 has 2 divisors, whose sum is σ = 515682. Its totient is φ = 515680.

The previous prime is 515677. The next prime is 515687. The reversal of 515681 is 186515.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 512656 + 3025 = 716^2 + 55^2 .

It is a cyclic number.

It is not a de Polignac number, because 515681 - 2² = 515677 is a prime.

It is a super-2 number, since 2×515681² = 531853787522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 515681.

It is not a weakly prime, because it can be changed into another prime (515687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 257840 + 257841.

It is an arithmetic number, because the mean of its divisors is an integer number (257841).

2⁵¹⁵⁶⁸¹ is an apocalyptic number.

It is an amenable number.

515681 is a deficient number, since it is larger than the sum of its proper divisors (1).

515681 is an equidigital number, since it uses as much as digits as its factorization.

515681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1200, while the sum is 26.

The square root of 515681 is about 718.1093231535. The cubic root of 515681 is about 80.1912611254.

The spelling of 515681 in words is "five hundred fifteen thousand, six hundred eighty-one".