6400636872 has 32 divisors (see below), whose sum is σ = 18287534400. Its totient is φ = 1828753344.

The previous prime is 6400636871. The next prime is 6400636883. The reversal of 6400636872 is 2786360046.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (6400636871) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 19049347 + ... + 19049682.

It is an arithmetic number, because the mean of its divisors is an integer number (571485450).

Almost surely, 2^6400636872 is an apocalyptic number.

It is an amenable number.

6400636872 is an abundant number, since it is smaller than the sum of its proper divisors (11886897528).

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

6400636872 is a wasteful number, since it uses less digits than its factorization.

6400636872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38099045 (or 38099041 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 42.

The square root of 6400636872 is about 80003.9803509800. The cubic root of 6400636872 is about 1856.6971167767.

The spelling of 6400636872 in words is "six billion, four hundred million, six hundred thirty-six thousand, eight hundred seventy-two".