645856 has 12 divisors (see below), whose sum is σ = 1271592. Its totient is φ = 322912.

The previous prime is 645851. The next prime is 645857. The reversal of 645856 is 658546.

645856 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10060 + ... + 10123.

It is an arithmetic number, because the mean of its divisors is an integer number (105966).

2⁶⁴⁵⁸⁵⁶ is an apocalyptic number.

It is an amenable number.

645856 is a deficient number, since it is larger than the sum of its proper divisors (625736).

645856 is a wasteful number, since it uses less digits than its factorization.

645856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20193 (or 20185 counting only the distinct ones).

The product of its digits is 28800, while the sum is 34.

The square root of 645856 is about 803.6516658354. The cubic root of 645856 is about 86.4394310187.

The spelling of 645856 in words is "six hundred forty-five thousand, eight hundred fifty-six".