640766847 has 8 divisors (see below), whose sum is σ = 976406656. Its totient is φ = 366152472.

The previous prime is 640766843. The next prime is 640766857. The reversal of 640766847 is 748667046.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 640766847 - 2² = 640766843 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 640766796 and 640766805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640766843) 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 7 ways as a sum of consecutive naturals, for example, 15256333 + ... + 15256374.

It is an arithmetic number, because the mean of its divisors is an integer number (122050832).

Almost surely, 2^640766847 is an apocalyptic number.

640766847 is a deficient number, since it is larger than the sum of its proper divisors (335639809).

640766847 is a wasteful number, since it uses less digits than its factorization.

640766847 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30512717.

The product of its (nonzero) digits is 1354752, while the sum is 48.

The square root of 640766847 is about 25313.3728886531. The cubic root of 640766847 is about 862.1179306713.

The spelling of 640766847 in words is "six hundred forty million, seven hundred sixty-six thousand, eight hundred forty-seven".