664720867 has 4 divisors (see below), whose sum is σ = 665437320. Its totient is φ = 664004416.

The previous prime is 664720813. The next prime is 664720883. The reversal of 664720867 is 768027466.

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 664720867 - 2⁷ = 664720739 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664720267) 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 3 ways as a sum of consecutive naturals, for example, 356833 + ... + 358690.

It is an arithmetic number, because the mean of its divisors is an integer number (166359330).

Almost surely, 2^664720867 is an apocalyptic number.

664720867 is a deficient number, since it is larger than the sum of its proper divisors (716453).

664720867 is an equidigital number, since it uses as much as digits as its factorization.

664720867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 716452.

The product of its (nonzero) digits is 677376, while the sum is 46.

The square root of 664720867 is about 25782.1811916680. The cubic root of 664720867 is about 872.7297302307.

The spelling of 664720867 in words is "six hundred sixty-four million, seven hundred twenty thousand, eight hundred sixty-seven".