644115 has 16 divisors (see below), whose sum is σ = 1075968. Its totient is φ = 328416.

The previous prime is 644107. The next prime is 644117. The reversal of 644115 is 511446.

644115 = T₄₃ + T₄₄ + ... + T₁₅₇.

It is not a de Polignac number, because 644115 - 2³ = 644107 is a prime.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 644091 and 644100.

It is not an unprimeable number, because it can be changed into a prime (644117) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 589 + ... + 1278.

It is an arithmetic number, because the mean of its divisors is an integer number (67248).

2⁶⁴⁴¹¹⁵ is an apocalyptic number.

644115 is a deficient number, since it is larger than the sum of its proper divisors (431853).

644115 is a wasteful number, since it uses less digits than its factorization.

644115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1898.

The product of its digits is 480, while the sum is 21.

The square root of 644115 is about 802.5677541491. The cubic root of 644115 is about 86.3616910499.

The spelling of 644115 in words is "six hundred forty-four thousand, one hundred fifteen".