6438491972640 has 3456 divisors, whose sum is σ = 31712292218880. Its totient is φ = 1170505728000.

The previous prime is 6438491972599. The next prime is 6438491972711. The reversal of 6438491972640 is 462791948346.

It is a happy number.

6438491972640 is a `hidden beast` number, since 6 + 4 + 38 + 491 + 9 + 72 + 6 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is an unprimeable number.

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 575 ways as a sum of consecutive naturals, for example, 9184724290 + ... + 9184724990.

It is an arithmetic number, because the mean of its divisors is an integer number (9176010480).

Almost surely, 2^{6438491972640} is an apocalyptic number.

6438491972640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6438491972640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15856146109440).

6438491972640 is an abundant number, since it is smaller than the sum of its proper divisors (25273800246240).

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

6438491972640 is a wasteful number, since it uses less digits than its factorization.

6438491972640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 816 (or 798 counting only the distinct ones).

The product of its (nonzero) digits is 62705664, while the sum is 63.

The spelling of 6438491972640 in words is "six trillion, four hundred thirty-eight billion, four hundred ninety-one million, nine hundred seventy-two thousand, six hundred forty".