509605991 has 4 divisors (see below), whose sum is σ = 539582832. Its totient is φ = 479629152.

The previous prime is 509605939. The next prime is 509605997. The reversal of 509605991 is 199506905.

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

It is a cyclic number.

It is not a de Polignac number, because 509605991 - 2¹⁰ = 509604967 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 (509605997) 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, 14988395 + ... + 14988428.

It is an arithmetic number, because the mean of its divisors is an integer number (134895708).

Almost surely, 2^509605991 is an apocalyptic number.

509605991 is a deficient number, since it is larger than the sum of its proper divisors (29976841).

509605991 is a wasteful number, since it uses less digits than its factorization.

509605991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29976840.

The product of its (nonzero) digits is 109350, while the sum is 44.

The square root of 509605991 is about 22574.4543898629. The cubic root of 509605991 is about 798.7511718622.

The spelling of 509605991 in words is "five hundred nine million, six hundred five thousand, nine hundred ninety-one".