644113 has 4 divisors (see below), whose sum is σ = 682020. Its totient is φ = 606208.

The previous prime is 644107. The next prime is 644117. The reversal of 644113 is 311446.

644113 = 567² + 568².

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 311446 = 2 ⋅155723.

It can be written as a sum of positive squares in 2 ways, for example, as 322624 + 321489 = 568^2 + 567^2 .

It is a cyclic number.

It is not a de Polignac number, because 644113 - 2¹⁷ = 513041 is a prime.

It is a Duffinian number.

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 3 ways as a sum of consecutive naturals, for example, 18928 + ... + 18961.

It is an arithmetic number, because the mean of its divisors is an integer number (170505).

2⁶⁴⁴¹¹³ is an apocalyptic number.

644113 is the 568-th centered square number.

It is an amenable number.

644113 is a deficient number, since it is larger than the sum of its proper divisors (37907).

644113 is a wasteful number, since it uses less digits than its factorization.

644113 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37906.

The product of its digits is 288, while the sum is 19.

The square root of 644113 is about 802.5665081475. The cubic root of 644113 is about 86.3616016645.

Adding to 644113 its reverse (311446), we get a palindrome (955559).

It can be divided in two parts, 644 and 113, that added together give a palindrome (757).

The spelling of 644113 in words is "six hundred forty-four thousand, one hundred thirteen".