644130 has 48 divisors (see below), whose sum is σ = 1777464. Its totient is φ = 161280.

The previous prime is 644129. The next prime is 644131. The reversal of 644130 is 31446.

It is an interprime number because it is at equal distance from previous prime (644129) and next prime (644131).

It can be written as a sum of positive squares in 4 ways, for example, as 393129 + 251001 = 627^2 + 501^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (644131) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1320 + ... + 1740.

2⁶⁴⁴¹³⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644130, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (888732).

644130 is an abundant number, since it is smaller than the sum of its proper divisors (1133334).

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

644130 is a wasteful number, since it uses less digits than its factorization.

644130 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 451 (or 448 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 644130 is about 802.5770991001. The cubic root of 644130 is about 86.3623614351.

Adding to 644130 its reverse (31446), we get a palindrome (675576).

The spelling of 644130 in words is "six hundred forty-four thousand, one hundred thirty".