642856 has 16 divisors (see below), whose sum is σ = 1218240. Its totient is φ = 318000.

The previous prime is 642853. The next prime is 642869. The reversal of 642856 is 658246.

642856 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (642853) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 481 + ... + 1231.

It is an arithmetic number, because the mean of its divisors is an integer number (76140).

642856 is a Friedman number, since it can be written as 8*(62*6^4+5), using all its digits and the basic arithmetic operations.

2⁶⁴²⁸⁵⁶ is an apocalyptic number.

It is an amenable number.

642856 is a deficient number, since it is larger than the sum of its proper divisors (575384).

642856 is a wasteful number, since it uses less digits than its factorization.

642856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 864 (or 860 counting only the distinct ones).

The product of its digits is 11520, while the sum is 31.

The square root of 642856 is about 801.7830130403. The cubic root of 642856 is about 86.3053862557.

The spelling of 642856 in words is "six hundred forty-two thousand, eight hundred fifty-six".