6440640375 has 32 divisors (see below), whose sum is σ = 11541636288. Its totient is φ = 3170774400.

The previous prime is 6440640361. The next prime is 6440640377. The reversal of 6440640375 is 5730460446.

It is a happy number.

It is not a de Polignac number, because 6440640375 - 2¹⁰ = 6440639351 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6440640377) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 655704 + ... + 665453.

It is an arithmetic number, because the mean of its divisors is an integer number (360676134).

Almost surely, 2^6440640375 is an apocalyptic number.

6440640375 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

6440640375 is a deficient number, since it is larger than the sum of its proper divisors (5100995913).

6440640375 is a wasteful number, since it uses less digits than its factorization.

6440640375 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1321188 (or 1321178 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 39.

The square root of 6440640375 is about 80253.6003865247. The cubic root of 6440640375 is about 1860.5571590790.

The spelling of 6440640375 in words is "six billion, four hundred forty million, six hundred forty thousand, three hundred seventy-five".