644905426 has 8 divisors (see below), whose sum is σ = 1055299824. Its totient is φ = 293138820.

The previous prime is 644905381. The next prime is 644905427. The reversal of 644905426 is 624509446.

It is a happy number.

644905426 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not an unprimeable number, because it can be changed into a prime (644905427) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14656920 + ... + 14656963.

It is an arithmetic number, because the mean of its divisors is an integer number (131912478).

Almost surely, 2^644905426 is an apocalyptic number.

644905426 is a deficient number, since it is larger than the sum of its proper divisors (410394398).

644905426 is a wasteful number, since it uses less digits than its factorization.

644905426 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29313896.

The product of its (nonzero) digits is 207360, while the sum is 40.

The square root of 644905426 is about 25394.9882063371. The cubic root of 644905426 is about 863.9700287171.

The spelling of 644905426 in words is "six hundred forty-four million, nine hundred five thousand, four hundred twenty-six".