644095 has 4 divisors (see below), whose sum is σ = 772920. Its totient is φ = 515272.

The previous prime is 644089. The next prime is 644101. The reversal of 644095 is 590446.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (644089) and next prime (644101).

It is a cyclic number.

It is not a de Polignac number, because 644095 - 2⁹ = 643583 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64405 + ... + 64414.

It is an arithmetic number, because the mean of its divisors is an integer number (193230).

2⁶⁴⁴⁰⁹⁵ is an apocalyptic number.

644095 is a deficient number, since it is larger than the sum of its proper divisors (128825).

644095 is a wasteful number, since it uses less digits than its factorization.

644095 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128824.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 644095 is about 802.5552940452. Note that the first 3 decimals coincide. The cubic root of 644095 is about 86.3607971869.

The spelling of 644095 in words is "six hundred forty-four thousand, ninety-five".