649966 has 4 divisors (see below), whose sum is σ = 974952. Its totient is φ = 324982.

The previous prime is 649937. The next prime is 649969. The reversal of 649966 is 669946.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 669946 = 2 ⋅334973.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (649969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 162490 + ... + 162493.

It is an arithmetic number, because the mean of its divisors is an integer number (243738).

2⁶⁴⁹⁹⁶⁶ is an apocalyptic number.

649966 is a deficient number, since it is larger than the sum of its proper divisors (324986).

649966 is a wasteful number, since it uses less digits than its factorization.

649966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324985.

The product of its digits is 69984, while the sum is 40.

The square root of 649966 is about 806.2046886492. The cubic root of 649966 is about 86.6224001421.

The spelling of 649966 in words is "six hundred forty-nine thousand, nine hundred sixty-six".