509991028 has 6 divisors (see below), whose sum is σ = 892484306. Its totient is φ = 254995512.

The previous prime is 509991019. The next prime is 509991043. The reversal of 509991028 is 820199905.

It can be written as a sum of positive squares in only one way, i.e., 324432144 + 185558884 = 18012^2 + 13622^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 63748875 + ... + 63748882.

Almost surely, 2^509991028 is an apocalyptic number.

It is an amenable number.

509991028 is a deficient number, since it is larger than the sum of its proper divisors (382493278).

509991028 is a wasteful number, since it uses less digits than its factorization.

509991028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127497761 (or 127497759 counting only the distinct ones).

The product of its (nonzero) digits is 58320, while the sum is 43.

The square root of 509991028 is about 22582.9809369800. The cubic root of 509991028 is about 798.9522888925.

The spelling of 509991028 in words is "five hundred nine million, nine hundred ninety-one thousand, twenty-eight".