645929 has 4 divisors (see below), whose sum is σ = 656580. Its totient is φ = 635280.

The previous prime is 645907. The next prime is 645937. The reversal of 645929 is 929546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 929546 = 2 ⋅464773.

It can be written as a sum of positive squares in 2 ways, for example, as 48400 + 597529 = 220^2 + 773^2 .

It is a cyclic number.

It is not a de Polignac number, because 645929 - 2¹² = 641833 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 (645979) 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, 5234 + ... + 5355.

It is an arithmetic number, because the mean of its divisors is an integer number (164145).

2⁶⁴⁵⁹²⁹ is an apocalyptic number.

It is an amenable number.

645929 is a deficient number, since it is larger than the sum of its proper divisors (10651).

645929 is a wasteful number, since it uses less digits than its factorization.

645929 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10650.

The product of its digits is 19440, while the sum is 35.

The square root of 645929 is about 803.6970822393. The cubic root of 645929 is about 86.4426875964.

It can be divided in two parts, 64 and 5929, that multiplied together give a square (379456 = 616²).

The spelling of 645929 in words is "six hundred forty-five thousand, nine hundred twenty-nine".