644616 has 48 divisors (see below), whose sum is σ = 1996800. Its totient is φ = 184032.

The previous prime is 644599. The next prime is 644617. The reversal of 644616 is 616446.

644616 is a `hidden beast` number, since 6 + 44 + 616 = 666.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 644616.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644617) by changing a digit.

644616 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 136 + ... + 1143.

It is an arithmetic number, because the mean of its divisors is an integer number (41600).

2⁶⁴⁴⁶¹⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (998400).

644616 is an abundant number, since it is smaller than the sum of its proper divisors (1352184).

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

644616 is a wasteful number, since it uses less digits than its factorization.

644616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1298 (or 1291 counting only the distinct ones).

The product of its digits is 3456, while the sum is 27.

The square root of 644616 is about 802.8798166600. The cubic root of 644616 is about 86.3840762835.

The spelling of 644616 in words is "six hundred forty-four thousand, six hundred sixteen".