644131 has 2 divisors, whose sum is σ = 644132. Its totient is φ = 644130.

The previous prime is 644129. The next prime is 644141. The reversal of 644131 is 131446.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644131 - 2¹ = 644129 is a prime.

It is a super-2 number, since 2×644131² = 829809490322, which contains 22 as substring.

Together with 644129, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 644099 and 644108.

It is not a weakly prime, because it can be changed into another prime (644101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322065 + 322066.

It is an arithmetic number, because the mean of its divisors is an integer number (322066).

2⁶⁴⁴¹³¹ is an apocalyptic number.

644131 is a deficient number, since it is larger than the sum of its proper divisors (1).

644131 is an equidigital number, since it uses as much as digits as its factorization.

644131 is an odious number, because the sum of its binary digits is odd.

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

The square root of 644131 is about 802.5777220930. The cubic root of 644131 is about 86.3624061270.

Adding to 644131 its reverse (131446), we get a palindrome (775577).

The spelling of 644131 in words is "six hundred forty-four thousand, one hundred thirty-one".