645247 has 4 divisors (see below), whose sum is σ = 654160. Its totient is φ = 636336.

The previous prime is 645233. The next prime is 645257. The reversal of 645247 is 742546.

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 645247 - 2¹¹ = 643199 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4347 + ... + 4492.

It is an arithmetic number, because the mean of its divisors is an integer number (163540).

2⁶⁴⁵²⁴⁷ is an apocalyptic number.

645247 is a deficient number, since it is larger than the sum of its proper divisors (8913).

645247 is an equidigital number, since it uses as much as digits as its factorization.

645247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8912.

The product of its digits is 6720, while the sum is 28.

The square root of 645247 is about 803.2726809745. The cubic root of 645247 is about 86.4122535633.

The spelling of 645247 in words is "six hundred forty-five thousand, two hundred forty-seven".