644430 has 16 divisors (see below), whose sum is σ = 1546704. Its totient is φ = 171840.

The previous prime is 644411. The next prime is 644431. The reversal of 644430 is 34446.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 644397 and 644406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10711 + ... + 10770.

It is an arithmetic number, because the mean of its divisors is an integer number (96669).

2⁶⁴⁴⁴³⁰ is an apocalyptic number.

644430 is an abundant number, since it is smaller than the sum of its proper divisors (902274).

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

644430 is a wasteful number, since it uses less digits than its factorization.

644430 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21491.

The product of its (nonzero) digits is 1152, while the sum is 21.

The square root of 644430 is about 802.7639752754. The cubic root of 644430 is about 86.3757669522.

Adding to 644430 its reverse (34446), we get a palindrome (678876).

The spelling of 644430 in words is "six hundred forty-four thousand, four hundred thirty".