644332140 has 36 divisors (see below), whose sum is σ = 1954474704. Its totient is φ = 171821856.

The previous prime is 644332111. The next prime is 644332141. The reversal of 644332140 is 41233446.

644332140 is a `hidden beast` number, since 6 + 443 + 3 + 214 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is not an unprimeable number, because it can be changed into a prime (644332141) 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 11 ways as a sum of consecutive naturals, for example, 1789632 + ... + 1789991.

It is an arithmetic number, because the mean of its divisors is an integer number (54290964).

Almost surely, 2^644332140 is an apocalyptic number.

644332140 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644332140 is an abundant number, since it is smaller than the sum of its proper divisors (1310142564).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644332140 is a wasteful number, since it uses less digits than its factorization.

644332140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3579638 (or 3579633 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 27.

The square root of 644332140 is about 25383.6983121057. The cubic root of 644332140 is about 863.7139452978.

Adding to 644332140 its reverse (41233446), we get a palindrome (685565586).

It can be divided in two parts, 6443 and 32140, that added together give a palindrome (38583).

The spelling of 644332140 in words is "six hundred forty-four million, three hundred thirty-two thousand, one hundred forty".