642878 has 8 divisors (see below), whose sum is σ = 995520. Its totient is φ = 311040.

The previous prime is 642877. The next prime is 642881. The reversal of 642878 is 878246.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 642878.

It is not an unprimeable number, because it can be changed into a prime (642871) 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 in 3 ways as a sum of consecutive naturals, for example, 5123 + ... + 5246.

It is an arithmetic number, because the mean of its divisors is an integer number (124440).

2⁶⁴²⁸⁷⁸ is an apocalyptic number.

642878 is a deficient number, since it is larger than the sum of its proper divisors (352642).

642878 is a wasteful number, since it uses less digits than its factorization.

642878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10402.

The product of its digits is 21504, while the sum is 35.

The square root of 642878 is about 801.7967323455. The cubic root of 642878 is about 86.3063707669.

The spelling of 642878 in words is "six hundred forty-two thousand, eight hundred seventy-eight".