644076077 has 4 divisors (see below), whose sum is σ = 644168700. Its totient is φ = 643983456.

The previous prime is 644076049. The next prime is 644076101. The reversal of 644076077 is 770670446.

644076077 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 532963396 + 111112681 = 23086^2 + 10541^2 .

It is a cyclic number.

It is not a de Polignac number, because 644076077 - 2²⁰ = 643027501 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644076047) 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, 34952 + ... + 50097.

It is an arithmetic number, because the mean of its divisors is an integer number (161042175).

Almost surely, 2^644076077 is an apocalyptic number.

It is an amenable number.

644076077 is a deficient number, since it is larger than the sum of its proper divisors (92623).

644076077 is an equidigital number, since it uses as much as digits as its factorization.

644076077 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92622.

The product of its (nonzero) digits is 197568, while the sum is 41.

The square root of 644076077 is about 25378.6539635182. The cubic root of 644076077 is about 863.5995144143.

The spelling of 644076077 in words is "six hundred forty-four million, seventy-six thousand, seventy-seven".