643777040 has 40 divisors (see below), whose sum is σ = 1500761088. Its totient is φ = 256826240.

The previous prime is 643777009. The next prime is 643777049. The reversal of 643777040 is 40777346.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 643776985 and 643777003.

It is not an unprimeable number, because it can be changed into a prime (643777049) 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, 20135 + ... + 41145.

Almost surely, 2^643777040 is an apocalyptic number.

It is an amenable number.

643777040 is an abundant number, since it is smaller than the sum of its proper divisors (856984048).

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

643777040 is a wasteful number, since it uses less digits than its factorization.

643777040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21407 (or 21401 counting only the distinct ones).

The product of its (nonzero) digits is 98784, while the sum is 38.

The square root of 643777040 is about 25372.7617732087. The cubic root of 643777040 is about 863.4658406685.

It can be divided in two parts, 64377 and 7040, that added together give a palindrome (71417).

The spelling of 643777040 in words is "six hundred forty-three million, seven hundred seventy-seven thousand, forty".