644544549 has 24 divisors (see below), whose sum is σ = 1016806752. Its totient is φ = 390186720.

The previous prime is 644544541. The next prime is 644544583. The reversal of 644544549 is 945445446.

644544549 is a `hidden beast` number, since 64 + 4 + 5 + 44 + 549 = 666.

644544549 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644544549 - 2³ = 644544541 is a prime.

It is a super-2 number, since 2×644544549² = 830875351291226802, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644544541) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 97074 + ... + 103500.

It is an arithmetic number, because the mean of its divisors is an integer number (42366948).

Almost surely, 2^644544549 is an apocalyptic number.

It is an amenable number.

644544549 is a deficient number, since it is larger than the sum of its proper divisors (372262203).

644544549 is a wasteful number, since it uses less digits than its factorization.

644544549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7457 (or 7454 counting only the distinct ones).

The product of its digits is 1382400, while the sum is 45.

The square root of 644544549 is about 25387.8819321345. The cubic root of 644544549 is about 863.8088448317.

The spelling of 644544549 in words is "six hundred forty-four million, five hundred forty-four thousand, five hundred forty-nine".