664817651543 has 4 divisors (see below), whose sum is σ = 703924572240. Its totient is φ = 625710730848.

The previous prime is 664817651539. The next prime is 664817651549. The reversal of 664817651543 is 345156718466.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 664817651543 - 2² = 664817651539 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664817651549) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19553460323 + ... + 19553460356.

It is an arithmetic number, because the mean of its divisors is an integer number (175981143060).

Almost surely, 2^664817651543 is an apocalyptic number.

664817651543 is a deficient number, since it is larger than the sum of its proper divisors (39106920697).

664817651543 is a wasteful number, since it uses less digits than its factorization.

664817651543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39106920696.

The product of its digits is 14515200, while the sum is 56.

The spelling of 664817651543 in words is "six hundred sixty-four billion, eight hundred seventeen million, six hundred fifty-one thousand, five hundred forty-three".