644330405 has 16 divisors (see below), whose sum is σ = 782221440. Its totient is φ = 509467968.

The previous prime is 644330387. The next prime is 644330419. The reversal of 644330405 is 504033446.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644330405 is a prime.

It is a congruent number.

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, 379739 + ... + 381431.

It is an arithmetic number, because the mean of its divisors is an integer number (48888840).

Almost surely, 2^644330405 is an apocalyptic number.

It is an amenable number.

644330405 is a deficient number, since it is larger than the sum of its proper divisors (137891035).

644330405 is a wasteful number, since it uses less digits than its factorization.

644330405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2540.

The product of its (nonzero) digits is 17280, while the sum is 29.

The square root of 644330405 is about 25383.6641366057. The cubic root of 644330405 is about 863.7131700532.

The spelling of 644330405 in words is "six hundred forty-four million, three hundred thirty thousand, four hundred five".