642866 has 16 divisors (see below), whose sum is σ = 1126656. Its totient is φ = 269376.

The previous prime is 642853. The next prime is 642869. The reversal of 642866 is 668246.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (642869) by changing a digit.

642866 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 in 7 ways as a sum of consecutive naturals, for example, 170 + ... + 1146.

It is an arithmetic number, because the mean of its divisors is an integer number (70416).

2⁶⁴²⁸⁶⁶ is an apocalyptic number.

642866 is a deficient number, since it is larger than the sum of its proper divisors (483790).

642866 is a wasteful number, since it uses less digits than its factorization.

642866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1033.

The product of its digits is 13824, while the sum is 32.

The square root of 642866 is about 801.7892491172. The cubic root of 642866 is about 86.3058337636.

The spelling of 642866 in words is "six hundred forty-two thousand, eight hundred sixty-six".