643491992678 has 16 divisors (see below), whose sum is σ = 968957295264. Its totient is φ = 320508601920.

The previous prime is 643491992677. The next prime is 643491992683. The reversal of 643491992678 is 876299194346.

It is a super-2 number, since 2×643491992678² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643491992677) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 50543 + ... + 1135578.

It is an arithmetic number, because the mean of its divisors is an integer number (60559830954).

Almost surely, 2^643491992678 is an apocalyptic number.

643491992678 is a deficient number, since it is larger than the sum of its proper divisors (325465302586).

643491992678 is a wasteful number, since it uses less digits than its factorization.

643491992678 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1187167.

The product of its digits is 141087744, while the sum is 68.

The spelling of 643491992678 in words is "six hundred forty-three billion, four hundred ninety-one million, nine hundred ninety-two thousand, six hundred seventy-eight".