6491320638 has 48 divisors (see below), whose sum is σ = 14281614480. Its totient is φ = 1965490560.

The previous prime is 6491320631. The next prime is 6491320651. The reversal of 6491320638 is 8360231946.

It is a self number, because there is not a number n which added to its sum of digits gives 6491320638.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6491320631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1165356 + ... + 1170912.

It is an arithmetic number, because the mean of its divisors is an integer number (297533635).

Almost surely, 2^6491320638 is an apocalyptic number.

6491320638 is an abundant number, since it is smaller than the sum of its proper divisors (7790293842).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6491320638 is a wasteful number, since it uses less digits than its factorization.

6491320638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7193 (or 7182 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 42.

The square root of 6491320638 is about 80568.7323842196. The cubic root of 6491320638 is about 1865.4245464744.

The spelling of 6491320638 in words is "six billion, four hundred ninety-one million, three hundred twenty thousand, six hundred thirty-eight".