645271 has 4 divisors (see below), whose sum is σ = 703944. Its totient is φ = 586600.

The previous prime is 645257. The next prime is 645313. The reversal of 645271 is 172546.

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 645271 - 2¹³ = 637079 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 (645571) 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, 29320 + ... + 29341.

It is an arithmetic number, because the mean of its divisors is an integer number (175986).

2⁶⁴⁵²⁷¹ is an apocalyptic number.

645271 is a deficient number, since it is larger than the sum of its proper divisors (58673).

645271 is a wasteful number, since it uses less digits than its factorization.

645271 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58672.

The product of its digits is 1680, while the sum is 25.

The square root of 645271 is about 803.2876197228. The cubic root of 645271 is about 86.4133249196.

It can be divided in two parts, 64 and 5271, that added together give a palindrome (5335).

The spelling of 645271 in words is "six hundred forty-five thousand, two hundred seventy-one".