644649377 has 4 divisors (see below), whose sum is σ = 644934276. Its totient is φ = 644364480.

The previous prime is 644649361. The next prime is 644649389. The reversal of 644649377 is 773946446.

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 180203776 + 464445601 = 13424^2 + 21551^2 .

It is a cyclic number.

It is not a de Polignac number, because 644649377 - 2⁴ = 644649361 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644649307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139028 + ... + 143589.

It is an arithmetic number, because the mean of its divisors is an integer number (161233569).

Almost surely, 2^644649377 is an apocalyptic number.

It is an amenable number.

644649377 is a deficient number, since it is larger than the sum of its proper divisors (284899).

644649377 is a wasteful number, since it uses less digits than its factorization.

644649377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284898.

The product of its digits is 3048192, while the sum is 50.

The square root of 644649377 is about 25389.9463764696. The cubic root of 644649377 is about 863.8556719260.

The spelling of 644649377 in words is "six hundred forty-four million, six hundred forty-nine thousand, three hundred seventy-seven".