644431063 has 4 divisors (see below), whose sum is σ = 644601160. Its totient is φ = 644260968.

The previous prime is 644431061. The next prime is 644431091. The reversal of 644431063 is 360134446.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 644431063 - 2¹ = 644431061 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 (644431061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 79233 + ... + 86986.

It is an arithmetic number, because the mean of its divisors is an integer number (161150290).

Almost surely, 2^644431063 is an apocalyptic number.

644431063 is a deficient number, since it is larger than the sum of its proper divisors (170097).

644431063 is a wasteful number, since it uses less digits than its factorization.

644431063 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170096.

The product of its (nonzero) digits is 20736, while the sum is 31.

The square root of 644431063 is about 25385.6467910510. The cubic root of 644431063 is about 863.7581444497.

The spelling of 644431063 in words is "six hundred forty-four million, four hundred thirty-one thousand, sixty-three".