517981 has 2 divisors, whose sum is σ = 517982. Its totient is φ = 517980.

The previous prime is 517967. The next prime is 517991. The reversal of 517981 is 189715.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 422500 + 95481 = 650^2 + 309^2 .

It is a cyclic number.

It is not a de Polignac number, because 517981 - 2⁵ = 517949 is a prime.

It is a super-2 number, since 2×517981² = 536608632722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (517901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 258990 + 258991.

It is an arithmetic number, because the mean of its divisors is an integer number (258991).

2⁵¹⁷⁹⁸¹ is an apocalyptic number.

It is an amenable number.

517981 is a deficient number, since it is larger than the sum of its proper divisors (1).

517981 is an equidigital number, since it uses as much as digits as its factorization.

517981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2520, while the sum is 31.

The square root of 517981 is about 719.7089689590. The cubic root of 517981 is about 80.3103052437.

The spelling of 517981 in words is "five hundred seventeen thousand, nine hundred eighty-one".