644554 has 8 divisors (see below), whose sum is σ = 1000260.
Its totient is φ = 311136.
The previous prime is 644549. The next prime is 644557. The reversal of 644554 is 455446.
It can be written as a sum of positive squares in 2 ways, for example, as 570025 + 74529 = 755^2 + 273^2
It is a sphenic number, since it is the product of 3 distinct primes.
It is a super-3 number, since 3×6445543 = 803339605091230392, which contains 333 as substring.
It is not an unprimeable number, because it can be changed into a prime (644557) 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 3 ways as a sum of consecutive naturals, for example, 5499 + ... + 5614.
2644554 is an apocalyptic number.
644554 is a deficient number, since it is larger than the sum of its proper divisors (355706).
644554 is a wasteful number, since it uses less digits than its factorization.
644554 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 11144.
The product of its digits is 9600, while the sum is 28.
The square root of 644554 is about 802.8412047223.
The cubic root of 644554 is about 86.3813066840.
The spelling of 644554 in words is "six hundred forty-four thousand, five hundred fifty-four".