644850505 has 8 divisors (see below), whose sum is σ = 833345352. Its totient is φ = 476197248.

The previous prime is 644850497. The next prime is 644850529. The reversal of 644850505 is 505058446.

It can be written as a sum of positive squares in 4 ways, for example, as 1923769 + 642926736 = 1387^2 + 25356^2 .

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 644850505 - 2³ = 644850497 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4960324 + ... + 4960453.

It is an arithmetic number, because the mean of its divisors is an integer number (104168169).

Almost surely, 2^644850505 is an apocalyptic number.

644850505 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

644850505 is a deficient number, since it is larger than the sum of its proper divisors (188494847).

644850505 is a wasteful number, since it uses less digits than its factorization.

644850505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9920795.

The product of its (nonzero) digits is 96000, while the sum is 37.

The square root of 644850505 is about 25393.9068479035. The cubic root of 644850505 is about 863.9455024104.

It can be divided in two parts, 6448 and 50505, that added together give a triangular number (56953 = T₃₃₇).

The spelling of 644850505 in words is "six hundred forty-four million, eight hundred fifty thousand, five hundred five".