644158 has 4 divisors (see below), whose sum is σ = 966240. Its totient is φ = 322078.

The previous prime is 644153. The next prime is 644159. The reversal of 644158 is 851446.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644153) by changing a digit.

644158 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 as a sum of consecutive naturals, namely, 161038 + ... + 161041.

It is an arithmetic number, because the mean of its divisors is an integer number (241560).

2⁶⁴⁴¹⁵⁸ is an apocalyptic number.

644158 is a deficient number, since it is larger than the sum of its proper divisors (322082).

644158 is a wasteful number, since it uses less digits than its factorization.

644158 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322081.

The product of its digits is 3840, while the sum is 28.

The square root of 644158 is about 802.5945427176. The cubic root of 644158 is about 86.3636127927.

The spelling of 644158 in words is "six hundred forty-four thousand, one hundred fifty-eight".