644140777 has 8 divisors (see below), whose sum is σ = 737676416. Its totient is φ = 550984032.

The previous prime is 644140771. The next prime is 644140801. The reversal of 644140777 is 777041446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644140777 - 2²⁷ = 509923049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644140771) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 91068 + ... + 97885.

It is an arithmetic number, because the mean of its divisors is an integer number (92209552).

Almost surely, 2^644140777 is an apocalyptic number.

It is an amenable number.

644140777 is a deficient number, since it is larger than the sum of its proper divisors (93535639).

644140777 is a wasteful number, since it uses less digits than its factorization.

644140777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189447.

The product of its (nonzero) digits is 131712, while the sum is 40.

The square root of 644140777 is about 25379.9286248011. The cubic root of 644140777 is about 863.6284307798.

The spelling of 644140777 in words is "six hundred forty-four million, one hundred forty thousand, seven hundred seventy-seven".