644238330 has 32 divisors (see below), whose sum is σ = 1583886528. Its totient is φ = 167606400.

The previous prime is 644238319. The next prime is 644238347. The reversal of 644238330 is 33832446.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 644238291 and 644238300.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 260656 + ... + 263115.

It is an arithmetic number, because the mean of its divisors is an integer number (49496454).

Almost surely, 2^644238330 is an apocalyptic number.

644238330 is an abundant number, since it is smaller than the sum of its proper divisors (939648198).

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

644238330 is a wasteful number, since it uses less digits than its factorization.

644238330 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 523822.

The product of its (nonzero) digits is 41472, while the sum is 33.

The square root of 644238330 is about 25381.8504053586. The cubic root of 644238330 is about 863.6720264733.

The spelling of 644238330 in words is "six hundred forty-four million, two hundred thirty-eight thousand, three hundred thirty".