664823647 has 4 divisors (see below), whose sum is σ = 674746456. Its totient is φ = 654900840.

The previous prime is 664823639. The next prime is 664823683. The reversal of 664823647 is 746328466.

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 664823647 - 2³ = 664823639 is a prime.

It is a super-2 number, since 2×664823647² = 883980963220761218, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 664823597 and 664823606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664823447) 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, 4961304 + ... + 4961437.

It is an arithmetic number, because the mean of its divisors is an integer number (168686614).

Almost surely, 2^664823647 is an apocalyptic number.

664823647 is a gapful number since it is divisible by the number (67) formed by its first and last digit.

664823647 is the 14887-th hex number.

664823647 is a deficient number, since it is larger than the sum of its proper divisors (9922809).

664823647 is an equidigital number, since it uses as much as digits as its factorization.

664823647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9922808.

The product of its digits is 1161216, while the sum is 46.

The square root of 664823647 is about 25784.1743517220. The cubic root of 664823647 is about 872.7747087790.

The spelling of 664823647 in words is "six hundred sixty-four million, eight hundred twenty-three thousand, six hundred forty-seven".