643879056 has 40 divisors (see below), whose sum is σ = 1665634464. Its totient is φ = 214332160.

The previous prime is 643879051. The next prime is 643879079. The reversal of 643879056 is 650978346.

It is a super-2 number, since 2×643879056² = 829160477510902272, which contains 22 as substring.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a junction number, because it is equal to n+sod(n) for n = 643878996 and 643879014.

It is not an unprimeable number, because it can be changed into a prime (643879051) 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, 27715 + ... + 45341.

Almost surely, 2^643879056 is an apocalyptic number.

It is an amenable number.

643879056 is an abundant number, since it is smaller than the sum of its proper divisors (1021755408).

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

643879056 is a wasteful number, since it uses less digits than its factorization.

643879056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18399 (or 18393 counting only the distinct ones).

The product of its (nonzero) digits is 1088640, while the sum is 48.

The square root of 643879056 is about 25374.7720383849. The cubic root of 643879056 is about 863.5114479068.

The spelling of 643879056 in words is "six hundred forty-three million, eight hundred seventy-nine thousand, fifty-six".