644064541 has 4 divisors (see below), whose sum is σ = 649973500. Its totient is φ = 638155584.

The previous prime is 644064539. The next prime is 644064557. The reversal of 644064541 is 145460446.

644064541 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 563872516 + 80192025 = 23746^2 + 8955^2 .

It is a cyclic number.

It is not a de Polignac number, because 644064541 - 2¹ = 644064539 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644064497 and 644064506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644064581) 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, 2954316 + ... + 2954533.

It is an arithmetic number, because the mean of its divisors is an integer number (162493375).

Almost surely, 2^644064541 is an apocalyptic number.

It is an amenable number.

644064541 is a deficient number, since it is larger than the sum of its proper divisors (5908959).

644064541 is a wasteful number, since it uses less digits than its factorization.

644064541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5908958.

The product of its (nonzero) digits is 46080, while the sum is 34.

The square root of 644064541 is about 25378.4266848834. The cubic root of 644064541 is about 863.5943584274.

The spelling of 644064541 in words is "six hundred forty-four million, sixty-four thousand, five hundred forty-one".