501665609 has 4 divisors (see below), whose sum is σ = 502318740. Its totient is φ = 501012480.

The previous prime is 501665603. The next prime is 501665611. The reversal of 501665609 is 906566105.

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

It can be written as a sum of positive squares in 2 ways, for example, as 191905609 + 309760000 = 13853^2 + 17600^2 .

It is a cyclic number.

It is not a de Polignac number, because 501665609 - 2¹² = 501661513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (501665603) 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, 325412 + ... + 326949.

It is an arithmetic number, because the mean of its divisors is an integer number (125579685).

Almost surely, 2^501665609 is an apocalyptic number.

It is an amenable number.

501665609 is a deficient number, since it is larger than the sum of its proper divisors (653131).

501665609 is an equidigital number, since it uses as much as digits as its factorization.

501665609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 653130.

The product of its (nonzero) digits is 48600, while the sum is 38.

The square root of 501665609 is about 22397.8929589370. The cubic root of 501665609 is about 794.5808789836.

The spelling of 501665609 in words is "five hundred one million, six hundred sixty-five thousand, six hundred nine".