6438635820 has 72 divisors (see below), whose sum is σ = 19553277744. Its totient is φ = 1714969728.

The previous prime is 6438635813. The next prime is 6438635873. The reversal of 6438635820 is 285368346.

It is a happy number.

6438635820 is a `hidden beast` number, since 6 + 4 + 3 + 8 + 63 + 582 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 137467 + ... + 178253.

It is an arithmetic number, because the mean of its divisors is an integer number (271573302).

Almost surely, 2^6438635820 is an apocalyptic number.

6438635820 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

6438635820 is an abundant number, since it is smaller than the sum of its proper divisors (13114641924).

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

6438635820 is a wasteful number, since it uses less digits than its factorization.

6438635820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41679 (or 41674 counting only the distinct ones).

The product of its (nonzero) digits is 829440, while the sum is 45.

The square root of 6438635820 is about 80241.1105356849. The cubic root of 6438635820 is about 1860.3641153270.

The spelling of 6438635820 in words is "six billion, four hundred thirty-eight million, six hundred thirty-five thousand, eight hundred twenty".