645263 has 4 divisors (see below), whose sum is σ = 659040. Its totient is φ = 631488.

The previous prime is 645257. The next prime is 645313. The reversal of 645263 is 362546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 362546 = 2 ⋅181273.

It is a cyclic number.

It is not a de Polignac number, because 645263 - 2¹⁰ = 644239 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645233) 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, 6818 + ... + 6911.

It is an arithmetic number, because the mean of its divisors is an integer number (164760).

2⁶⁴⁵²⁶³ is an apocalyptic number.

645263 is a deficient number, since it is larger than the sum of its proper divisors (13777).

645263 is a wasteful number, since it uses less digits than its factorization.

645263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13776.

The product of its digits is 4320, while the sum is 26.

The square root of 645263 is about 803.2826401709. The cubic root of 645263 is about 86.4129678038.

The spelling of 645263 in words is "six hundred forty-five thousand, two hundred sixty-three".