509921 has 2 divisors, whose sum is σ = 509922. Its totient is φ = 509920.

The previous prime is 509911. The next prime is 509939. The reversal of 509921 is 129905.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 483025 + 26896 = 695^2 + 164^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-509921 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (509911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 254960 + 254961.

It is an arithmetic number, because the mean of its divisors is an integer number (254961).

2⁵⁰⁹⁹²¹ is an apocalyptic number.

It is an amenable number.

509921 is a deficient number, since it is larger than the sum of its proper divisors (1).

509921 is an equidigital number, since it uses as much as digits as its factorization.

509921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 810, while the sum is 26.

The square root of 509921 is about 714.0875296489. The cubic root of 509921 is about 79.8915718581.

The spelling of 509921 in words is "five hundred nine thousand, nine hundred twenty-one".