646646647 has 4 divisors (see below), whose sum is σ = 647997120. Its totient is φ = 645296176.

The previous prime is 646646641. The next prime is 646646653. The reversal of 646646647 is 746646646.

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

It is an interprime number because it is at equal distance from previous prime (646646641) and next prime (646646653).

It is a cyclic number.

It is not a de Polignac number, because 646646647 - 2¹¹ = 646644599 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 646646647.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646646641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 674518 + ... + 675475.

It is an arithmetic number, because the mean of its divisors is an integer number (161999280).

Almost surely, 2^646646647 is an apocalyptic number.

646646647 is a deficient number, since it is larger than the sum of its proper divisors (1350473).

646646647 is a wasteful number, since it uses less digits than its factorization.

646646647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1350472.

The product of its digits is 3483648, while the sum is 49.

The square root of 646646647 is about 25429.2478654010. The cubic root of 646646647 is about 864.7468924328.

Subtracting 646646647 from its reverse (746646646), we obtain a palindrome (99999999).

The spelling of 646646647 in words is "six hundred forty-six million, six hundred forty-six thousand, six hundred forty-seven".