643640763 has 8 divisors (see below), whose sum is σ = 895500288. Its totient is φ = 410437544.

The previous prime is 643640747. The next prime is 643640779. The reversal of 643640763 is 367046346.

It is an interprime number because it is at equal distance from previous prime (643640747) and next prime (643640779).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 643640763 - 2⁴ = 643640747 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643640743) 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, 4663995 + ... + 4664132.

It is an arithmetic number, because the mean of its divisors is an integer number (111937536).

Almost surely, 2^643640763 is an apocalyptic number.

643640763 is a deficient number, since it is larger than the sum of its proper divisors (251859525).

643640763 is a wasteful number, since it uses less digits than its factorization.

643640763 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9328153.

The product of its (nonzero) digits is 217728, while the sum is 39.

The square root of 643640763 is about 25370.0761331140. The cubic root of 643640763 is about 863.4049092015.

The spelling of 643640763 in words is "six hundred forty-three million, six hundred forty thousand, seven hundred sixty-three".