643680217787 has 16 divisors (see below), whose sum is σ = 661268803104. Its totient is φ = 626184192000.

The previous prime is 643680217753. The next prime is 643680217811. The reversal of 643680217787 is 787712086346.

It is a cyclic number.

It is not a de Polignac number, because 643680217787 - 2²⁶ = 643613108923 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643680277787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20667587 + ... + 20698707.

It is an arithmetic number, because the mean of its divisors is an integer number (41329300194).

Almost surely, 2^643680217787 is an apocalyptic number.

643680217787 is a deficient number, since it is larger than the sum of its proper divisors (17588585317).

643680217787 is a wasteful number, since it uses less digits than its factorization.

643680217787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32590.

The product of its (nonzero) digits is 18966528, while the sum is 59.

The spelling of 643680217787 in words is "six hundred forty-three billion, six hundred eighty million, two hundred seventeen thousand, seven hundred eighty-seven".