644242 has 8 divisors (see below), whose sum is σ = 997632. Its totient is φ = 311700.

The previous prime is 644239. The next prime is 644257. The reversal of 644242 is 242446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5134 + ... + 5257.

It is an arithmetic number, because the mean of its divisors is an integer number (124704).

2⁶⁴⁴²⁴² is an apocalyptic number.

644242 is a gapful number since it is divisible by the number (62) formed by its first and last digit.

644242 is a deficient number, since it is larger than the sum of its proper divisors (353390).

644242 is a wasteful number, since it uses less digits than its factorization.

644242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10424.

The product of its digits is 1536, while the sum is 22.

The square root of 644242 is about 802.6468712952. The cubic root of 644242 is about 86.3673666482.

Adding to 644242 its reverse (242446), we get a palindrome (886688).

The spelling of 644242 in words is "six hundred forty-four thousand, two hundred forty-two".