643982254464 has 128 divisors (see below), whose sum is σ = 1721668608000. Its totient is φ = 213273399296.

The previous prime is 643982254463. The next prime is 643982254483. The reversal of 643982254464 is 464452289346.

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-3 number, since 3×643982254464³ (a number of 36 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643982254463) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38671612 + ... + 38688260.

It is an arithmetic number, because the mean of its divisors is an integer number (13450536000).

Almost surely, 2^643982254464 is an apocalyptic number.

643982254464 is a gapful number since it is divisible by the number (64) 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 643982254464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (860834304000).

643982254464 is an abundant number, since it is smaller than the sum of its proper divisors (1077686353536).

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

643982254464 is a wasteful number, since it uses less digits than its factorization.

643982254464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17312 (or 17300 counting only the distinct ones).

The product of its digits is 39813120, while the sum is 57.

The spelling of 643982254464 in words is "six hundred forty-three billion, nine hundred eighty-two million, two hundred fifty-four thousand, four hundred sixty-four".