645773 has 4 divisors (see below), whose sum is σ = 647388. Its totient is φ = 644160.

The previous prime is 645763. The next prime is 645787. The reversal of 645773 is 377546.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 413449 + 232324 = 643^2 + 482^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645773 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

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

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 293 + ... + 1173.

It is an arithmetic number, because the mean of its divisors is an integer number (161847).

2⁶⁴⁵⁷⁷³ is an apocalyptic number.

It is an amenable number.

645773 is a deficient number, since it is larger than the sum of its proper divisors (1615).

645773 is an equidigital number, since it uses as much as digits as its factorization.

645773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1614.

The product of its digits is 17640, while the sum is 32.

The square root of 645773 is about 803.6000248880. The cubic root of 645773 is about 86.4357280364.

The spelling of 645773 in words is "six hundred forty-five thousand, seven hundred seventy-three".