64443641856 has 416 divisors, whose sum is σ = 206082938880. Its totient is φ = 17679974400.

The previous prime is 64443641851. The next prime is 64443641869. The reversal of 64443641856 is 65814634446.

It is a junction number, because it is equal to n+sod(n) for n = 64443641799 and 64443641808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64443641851) 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, 59067871 + ... + 59068961.

It is an arithmetic number, because the mean of its divisors is an integer number (495391680).

Almost surely, 2^64443641856 is an apocalyptic number.

64443641856 is a gapful number since it is divisible by the number (66) 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 64443641856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (103041469440).

64443641856 is an abundant number, since it is smaller than the sum of its proper divisors (141639297024).

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

64443641856 is a wasteful number, since it uses less digits than its factorization.

64443641856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1171 (or 1149 counting only the distinct ones).

The product of its digits is 6635520, while the sum is 51.

The spelling of 64443641856 in words is "sixty-four billion, four hundred forty-three million, six hundred forty-one thousand, eight hundred fifty-six".