643437968 has 10 divisors (see below), whose sum is σ = 1246661094. Its totient is φ = 321718976.

The previous prime is 643437961. The next prime is 643437989. The reversal of 643437968 is 869734346.

It can be written as a sum of positive squares in only one way, i.e., 582160384 + 61277584 = 24128^2 + 7828^2 .

It is not an unprimeable number, because it can be changed into a prime (643437961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20107421 + ... + 20107452.

Almost surely, 2^643437968 is an apocalyptic number.

It is an amenable number.

643437968 is a deficient number, since it is larger than the sum of its proper divisors (603223126).

643437968 is a wasteful number, since it uses less digits than its factorization.

643437968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40214881 (or 40214875 counting only the distinct ones).

The product of its digits is 2612736, while the sum is 50.

The square root of 643437968 is about 25366.0790821128. The cubic root of 643437968 is about 863.3142206264.

The spelling of 643437968 in words is "six hundred forty-three million, four hundred thirty-seven thousand, nine hundred sixty-eight".