644633065 has 16 divisors (see below), whose sum is σ = 799626240. Its totient is φ = 498375360.

The previous prime is 644633057. The next prime is 644633071. The reversal of 644633065 is 560336446.

644633065 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 644633065 - 2³ = 644633057 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 127567 + ... + 132523.

It is an arithmetic number, because the mean of its divisors is an integer number (49976640).

Almost surely, 2^644633065 is an apocalyptic number.

It is an amenable number.

644633065 is a deficient number, since it is larger than the sum of its proper divisors (154993175).

644633065 is a wasteful number, since it uses less digits than its factorization.

644633065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5832.

The product of its (nonzero) digits is 155520, while the sum is 37.

The square root of 644633065 is about 25389.6251449288. The cubic root of 644633065 is about 863.8483856227.

It can be divided in two parts, 64463 and 3065, that added together give a triangular number (67528 = T₃₆₇).

The spelling of 644633065 in words is "six hundred forty-four million, six hundred thirty-three thousand, sixty-five".