643516944 has 40 divisors (see below), whose sum is σ = 1899908160. Its totient is φ = 183861888.

The previous prime is 643516943. The next prime is 643516957. The reversal of 643516944 is 449615346.

It is a happy number.

It is a super-2 number, since 2×643516944² = 828228114430198272, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 643516896 and 643516905.

It is not an unprimeable number, because it can be changed into a prime (643516943) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 957279 + ... + 957950.

It is an arithmetic number, because the mean of its divisors is an integer number (47497704).

Almost surely, 2^643516944 is an apocalyptic number.

It is an amenable number.

643516944 is an abundant number, since it is smaller than the sum of its proper divisors (1256391216).

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

643516944 is a wasteful number, since it uses less digits than its factorization.

643516944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1915247 (or 1915241 counting only the distinct ones).

The product of its digits is 311040, while the sum is 42.

The square root of 643516944 is about 25367.6357589745. The cubic root of 643516944 is about 863.3495404334.

The spelling of 643516944 in words is "six hundred forty-three million, five hundred sixteen thousand, nine hundred forty-four".