647866 has 4 divisors (see below), whose sum is σ = 971802. Its totient is φ = 323932.

The previous prime is 647861. The next prime is 647891. The reversal of 647866 is 668746.

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

It can be written as a sum of positive squares in only one way, i.e., 570025 + 77841 = 755^2 + 279^2 .

It is not an unprimeable number, because it can be changed into a prime (647861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161965 + ... + 161968.

2⁶⁴⁷⁸⁶⁶ is an apocalyptic number.

647866 is a deficient number, since it is larger than the sum of its proper divisors (323936).

647866 is a wasteful number, since it uses less digits than its factorization.

647866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 323935.

The product of its digits is 48384, while the sum is 37.

The square root of 647866 is about 804.9012361775. The cubic root of 647866 is about 86.5290089479.

The spelling of 647866 in words is "six hundred forty-seven thousand, eight hundred sixty-six".