515981 has 4 divisors (see below), whose sum is σ = 518364. Its totient is φ = 513600.

The previous prime is 515969. The next prime is 515993. The reversal of 515981 is 189515.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (515969) and next prime (515993).

It can be written as a sum of positive squares in 2 ways, for example, as 448900 + 67081 = 670^2 + 259^2 .

It is a cyclic number.

It is not a de Polignac number, because 515981 - 2⁶ = 515917 is a prime.

It is a super-2 number, since 2×515981² = 532472784722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (515941) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 830 + ... + 1311.

It is an arithmetic number, because the mean of its divisors is an integer number (129591).

2⁵¹⁵⁹⁸¹ is an apocalyptic number.

It is an amenable number.

515981 is a deficient number, since it is larger than the sum of its proper divisors (2383).

515981 is a wasteful number, since it uses less digits than its factorization.

515981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2382.

The product of its digits is 1800, while the sum is 29.

The square root of 515981 is about 718.3181746274. The cubic root of 515981 is about 80.2068086665.

The spelling of 515981 in words is "five hundred fifteen thousand, nine hundred eighty-one".