644826841 has 2 divisors, whose sum is σ = 644826842. Its totient is φ = 644826840.

The previous prime is 644826823. The next prime is 644826851. The reversal of 644826841 is 148628446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 596385241 + 48441600 = 24421^2 + 6960^2 .

It is a cyclic number.

It is not a de Polignac number, because 644826841 - 2¹⁷ = 644695769 is a prime.

It is not a weakly prime, because it can be changed into another prime (644826811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322413420 + 322413421.

It is an arithmetic number, because the mean of its divisors is an integer number (322413421).

Almost surely, 2^644826841 is an apocalyptic number.

It is an amenable number.

644826841 is a deficient number, since it is larger than the sum of its proper divisors (1).

644826841 is an equidigital number, since it uses as much as digits as its factorization.

644826841 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 294912, while the sum is 43.

The square root of 644826841 is about 25393.4409050841. The cubic root of 644826841 is about 863.9349342470.

The spelling of 644826841 in words is "six hundred forty-four million, eight hundred twenty-six thousand, eight hundred forty-one".