644634541 has 2 divisors, whose sum is σ = 644634542. Its totient is φ = 644634540.

The previous prime is 644634517. The next prime is 644634583. The reversal of 644634541 is 145436446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 574560900 + 70073641 = 23970^2 + 8371^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644634541 is a prime.

It is a super-3 number, since 3×644634541³ (a number of 27 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 644634541.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644634511) 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, 322317270 + 322317271.

It is an arithmetic number, because the mean of its divisors is an integer number (322317271).

Almost surely, 2^644634541 is an apocalyptic number.

It is an amenable number.

644634541 is a deficient number, since it is larger than the sum of its proper divisors (1).

644634541 is an equidigital number, since it uses as much as digits as its factorization.

644634541 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 138240, while the sum is 37.

The square root of 644634541 is about 25389.6542119029. The cubic root of 644634541 is about 863.8490449328.

The spelling of 644634541 in words is "six hundred forty-four million, six hundred thirty-four thousand, five hundred forty-one".