647640317 has 4 divisors (see below), whose sum is σ = 651031296. Its totient is φ = 644249340.

The previous prime is 647640299. The next prime is 647640319. The reversal of 647640317 is 713046746.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-647640317 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 (647640319) 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, 1695203 + ... + 1695584.

It is an arithmetic number, because the mean of its divisors is an integer number (162757824).

Almost surely, 2^647640317 is an apocalyptic number.

It is an amenable number.

647640317 is a deficient number, since it is larger than the sum of its proper divisors (3390979).

647640317 is a wasteful number, since it uses less digits than its factorization.

647640317 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3390978.

The product of its (nonzero) digits is 84672, while the sum is 38.

The square root of 647640317 is about 25448.7783007358. The cubic root of 647640317 is about 865.1896037084.

The spelling of 647640317 in words is "six hundred forty-seven million, six hundred forty thousand, three hundred seventeen".