643664441523 has 16 divisors (see below), whose sum is σ = 902584590336. Its totient is φ = 407220770880.

The previous prime is 643664441503. The next prime is 643664441591. The reversal of 643664441523 is 325144466346.

It is not a de Polignac number, because 643664441523 - 2¹⁴ = 643664425139 is a prime.

It is a super-2 number, since 2×643664441523² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (643664441503) 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, 36717498 + ... + 36735023.

It is an arithmetic number, because the mean of its divisors is an integer number (56411536896).

Almost surely, 2^643664441523 is an apocalyptic number.

643664441523 is a deficient number, since it is larger than the sum of its proper divisors (258920148813).

643664441523 is a wasteful number, since it uses less digits than its factorization.

643664441523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73452674.

The product of its digits is 4976640, while the sum is 48.

The spelling of 643664441523 in words is "six hundred forty-three billion, six hundred sixty-four million, four hundred forty-one thousand, five hundred twenty-three".