643961472 has 256 divisors, whose sum is σ = 2209075200. Its totient is φ = 161280000.

The previous prime is 643961467. The next prime is 643961473. The reversal of 643961472 is 274169346.

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 (643961473) 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, 857097 + ... + 857847.

It is an arithmetic number, because the mean of its divisors is an integer number (8629200).

Almost surely, 2^643961472 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643961472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1104537600).

643961472 is an abundant number, since it is smaller than the sum of its proper divisors (1565113728).

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

643961472 is a wasteful number, since it uses less digits than its factorization.

643961472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 815 (or 803 counting only the distinct ones).

The product of its digits is 217728, while the sum is 42.

The square root of 643961472 is about 25376.3959616018. The cubic root of 643961472 is about 863.5482892580.

The spelling of 643961472 in words is "six hundred forty-three million, nine hundred sixty-one thousand, four hundred seventy-two".