509125921 has 4 divisors (see below), whose sum is σ = 509815600. Its totient is φ = 508436244.

The previous prime is 509125913. The next prime is 509125931. The reversal of 509125921 is 129521905.

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: 129521905 = 5 ⋅25904381.

It is a cyclic number.

It is not a de Polignac number, because 509125921 - 2³ = 509125913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (509125931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 343731 + ... + 345208.

It is an arithmetic number, because the mean of its divisors is an integer number (127453900).

Almost surely, 2^509125921 is an apocalyptic number.

It is an amenable number.

509125921 is a deficient number, since it is larger than the sum of its proper divisors (689679).

509125921 is an equidigital number, since it uses as much as digits as its factorization.

509125921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 689678.

The product of its (nonzero) digits is 8100, while the sum is 34.

The square root of 509125921 is about 22563.8188478812. The cubic root of 509125921 is about 798.5002741389.

The spelling of 509125921 in words is "five hundred nine million, one hundred twenty-five thousand, nine hundred twenty-one".