664161643 has 4 divisors (see below), whose sum is σ = 675418680. Its totient is φ = 652904608.

The previous prime is 664161623. The next prime is 664161647. The reversal of 664161643 is 346161466.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664161643 is a prime.

It is a super-2 number, since 2×664161643² = 882221376064918898, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664161647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5628430 + ... + 5628547.

It is an arithmetic number, because the mean of its divisors is an integer number (168854670).

Almost surely, 2^664161643 is an apocalyptic number.

664161643 is a deficient number, since it is larger than the sum of its proper divisors (11257037).

664161643 is a wasteful number, since it uses less digits than its factorization.

664161643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11257036.

The product of its digits is 62208, while the sum is 37.

The square root of 664161643 is about 25771.3337450742. Note that the first 3 decimals coincide. The cubic root of 664161643 is about 872.4849215381.

The spelling of 664161643 in words is "six hundred sixty-four million, one hundred sixty-one thousand, six hundred forty-three".