643640764426 has 64 divisors (see below), whose sum is σ = 1108492646400. Its totient is φ = 277439722560.

The previous prime is 643640764421. The next prime is 643640764477. The reversal of 643640764426 is 624467046346.

It is not an unprimeable number, because it can be changed into a prime (643640764421) 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, 41232715 + ... + 41248321.

It is an arithmetic number, because the mean of its divisors is an integer number (17320197600).

Almost surely, 2^643640764426 is an apocalyptic number.

643640764426 is a deficient number, since it is larger than the sum of its proper divisors (464851881974).

643640764426 is a wasteful number, since it uses less digits than its factorization.

643640764426 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16339.

The product of its (nonzero) digits is 13934592, while the sum is 52.

The spelling of 643640764426 in words is "six hundred forty-three billion, six hundred forty million, seven hundred sixty-four thousand, four hundred twenty-six".