642668 has 24 divisors (see below), whose sum is σ = 1284192. Its totient is φ = 278784.

The previous prime is 642623. The next prime is 642673. The reversal of 642668 is 866246.

It is a happy number.

It is a Smith number, since the sum of its digits (32) coincides with the sum of the digits of its prime factors.

It is an Ulam number.

It is an unprimeable 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, 521 + ... + 1247.

It is an arithmetic number, because the mean of its divisors is an integer number (53508).

2⁶⁴²⁶⁶⁸ is an apocalyptic number.

642668 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

642668 is a deficient number, since it is larger than the sum of its proper divisors (641524).

642668 is a wasteful number, since it uses less digits than its factorization.

642668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 761 (or 759 counting only the distinct ones).

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

The square root of 642668 is about 801.6657657653. The cubic root of 642668 is about 86.2969722436.

The spelling of 642668 in words is "six hundred forty-two thousand, six hundred sixty-eight".