644155135 has 16 divisors (see below), whose sum is σ = 868641984. Its totient is φ = 455000832.

The previous prime is 644155133. The next prime is 644155153. The reversal of 644155135 is 531551446.

It is not a de Polignac number, because 644155135 - 2¹ = 644155133 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644155135.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644155133) 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 15 ways as a sum of consecutive naturals, for example, 213942 + ... + 216931.

It is an arithmetic number, because the mean of its divisors is an integer number (54290124).

Almost surely, 2^644155135 is an apocalyptic number.

644155135 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

644155135 is a deficient number, since it is larger than the sum of its proper divisors (224486849).

644155135 is a wasteful number, since it uses less digits than its factorization.

644155135 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 430914.

The product of its digits is 36000, while the sum is 34.

The square root of 644155135 is about 25380.2114845405. The cubic root of 644155135 is about 863.6348475370.

The spelling of 644155135 in words is "six hundred forty-four million, one hundred fifty-five thousand, one hundred thirty-five".