645747 has 4 divisors (see below), whose sum is σ = 861000. Its totient is φ = 430496.

The previous prime is 645739. The next prime is 645751. The reversal of 645747 is 747546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645747 - 2³ = 645739 is a prime.

It is a D-number.

It is not an unprimeable number, because it can be changed into a prime (645727) 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, 107622 + ... + 107627.

It is an arithmetic number, because the mean of its divisors is an integer number (215250).

2⁶⁴⁵⁷⁴⁷ is an apocalyptic number.

645747 is a deficient number, since it is larger than the sum of its proper divisors (215253).

645747 is a wasteful number, since it uses less digits than its factorization.

645747 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215252.

The product of its digits is 23520, while the sum is 33.

The square root of 645747 is about 803.5838475231. The cubic root of 645747 is about 86.4345680007.

It can be divided in two parts, 6 and 45747, that added together give a triangular number (45753 = T₃₀₂).

The spelling of 645747 in words is "six hundred forty-five thousand, seven hundred forty-seven".