644661041 has 2 divisors, whose sum is σ = 644661042. Its totient is φ = 644661040.

The previous prime is 644661037. The next prime is 644661047. The reversal of 644661041 is 140166446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 619810816 + 24850225 = 24896^2 + 4985^2 .

It is a cyclic number.

It is not a de Polignac number, because 644661041 - 2² = 644661037 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644660989 and 644661007.

It is not a weakly prime, because it can be changed into another prime (644661047) 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, 322330520 + 322330521.

It is an arithmetic number, because the mean of its divisors is an integer number (322330521).

Almost surely, 2^644661041 is an apocalyptic number.

It is an amenable number.

644661041 is a deficient number, since it is larger than the sum of its proper divisors (1).

644661041 is an equidigital number, since it uses as much as digits as its factorization.

644661041 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13824, while the sum is 32.

The square root of 644661041 is about 25390.1760726467. The cubic root of 644661041 is about 863.8608819684.

The spelling of 644661041 in words is "six hundred forty-four million, six hundred sixty-one thousand, forty-one".