645705 has 16 divisors (see below), whose sum is σ = 1148160. Its totient is φ = 344304.

The previous prime is 645703. The next prime is 645713. The reversal of 645705 is 507546.

645705 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 645705 - 2¹ = 645703 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (645703) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2257 + ... + 2526.

It is an arithmetic number, because the mean of its divisors is an integer number (71760).

2⁶⁴⁵⁷⁰⁵ is an apocalyptic number.

It is an amenable number.

645705 is a deficient number, since it is larger than the sum of its proper divisors (502455).

645705 is a wasteful number, since it uses less digits than its factorization.

645705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4797 (or 4791 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 27.

The square root of 645705 is about 803.5577141687. The cubic root of 645705 is about 86.4326940312.

The spelling of 645705 in words is "six hundred forty-five thousand, seven hundred five".