6440390509 has 12 divisors (see below), whose sum is σ = 7513369500. Its totient is φ = 5504502528.

The previous prime is 6440390501. The next prime is 6440390531. The reversal of 6440390509 is 9050930446.

It can be written as a sum of positive squares in 2 ways, for example, as 2502200484 + 3938190025 = 50022^2 + 62755^2 .

It is not a de Polignac number, because 6440390509 - 2³ = 6440390501 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6440390501) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 171204 + ... + 205405.

It is an arithmetic number, because the mean of its divisors is an integer number (626114125).

Almost surely, 2^6440390509 is an apocalyptic number.

It is an amenable number.

6440390509 is a deficient number, since it is larger than the sum of its proper divisors (1072978991).

6440390509 is a wasteful number, since it uses less digits than its factorization.

6440390509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 376972 (or 376965 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 40.

The square root of 6440390509 is about 80252.0436437603. The cubic root of 6440390509 is about 1860.5330985322.

The spelling of 6440390509 in words is "six billion, four hundred forty million, three hundred ninety thousand, five hundred nine".