647666671 has 4 divisors (see below), whose sum is σ = 647721712. Its totient is φ = 647611632.

The previous prime is 647666653. The next prime is 647666687. The reversal of 647666671 is 176666746.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 647666671 - 2²⁹ = 110795759 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 (647666651) 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, 1950 + ... + 36043.

It is an arithmetic number, because the mean of its divisors is an integer number (161930428).

Almost surely, 2^647666671 is an apocalyptic number.

647666671 is a deficient number, since it is larger than the sum of its proper divisors (55041).

647666671 is a wasteful number, since it uses less digits than its factorization.

647666671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55040.

The product of its digits is 1524096, while the sum is 49.

The square root of 647666671 is about 25449.2960806385. The cubic root of 647666671 is about 865.2013390790.

The spelling of 647666671 in words is "six hundred forty-seven million, six hundred sixty-six thousand, six hundred seventy-one".