509539991 has 2 divisors, whose sum is σ = 509539992. Its totient is φ = 509539990.

The previous prime is 509539973. The next prime is 509539993. The reversal of 509539991 is 199935905.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 509539991 - 2¹⁴ = 509523607 is a prime.

Together with 509539993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (509539993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 254769995 + 254769996.

It is an arithmetic number, because the mean of its divisors is an integer number (254769996).

Almost surely, 2^509539991 is an apocalyptic number.

509539991 is a deficient number, since it is larger than the sum of its proper divisors (1).

509539991 is an equidigital number, since it uses as much as digits as its factorization.

509539991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 492075, while the sum is 50.

The square root of 509539991 is about 22572.9925131782. The cubic root of 509539991 is about 798.7166878005.

The spelling of 509539991 in words is "five hundred nine million, five hundred thirty-nine thousand, nine hundred ninety-one".