509761 has 4 divisors (see below), whose sum is σ = 582592. Its totient is φ = 436932.

The previous prime is 509741. The next prime is 509767. The reversal of 509761 is 167905.

509761 = 89² + 90² + ... + 130².

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 167905 = 5 ⋅33581.

It is a cyclic number.

It is not a de Polignac number, because 509761 - 2⁷ = 509633 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (509767) 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, 36405 + ... + 36418.

It is an arithmetic number, because the mean of its divisors is an integer number (145648).

2⁵⁰⁹⁷⁶¹ is an apocalyptic number.

It is an amenable number.

509761 is a deficient number, since it is larger than the sum of its proper divisors (72831).

509761 is an equidigital number, since it uses as much as digits as its factorization.

509761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72830.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 509761 is about 713.9754897754. The cubic root of 509761 is about 79.8832150155.

The spelling of 509761 in words is "five hundred nine thousand, seven hundred sixty-one".