644064435 has 24 divisors (see below), whose sum is σ = 1275861600. Its totient is φ = 294429312.

The previous prime is 644064409. The next prime is 644064437. The reversal of 644064435 is 534460446.

644064435 is a `hidden beast` number, since 6 + 4 + 4 + 0 + 644 + 3 + 5 = 666.

644064435 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644064435 - 2⁷ = 644064307 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644064435.

It is not an unprimeable number, because it can be changed into a prime (644064437) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1022010 + ... + 1022639.

It is an arithmetic number, because the mean of its divisors is an integer number (53160900).

Almost surely, 2^644064435 is an apocalyptic number.

644064435 is a deficient number, since it is larger than the sum of its proper divisors (631797165).

644064435 is a wasteful number, since it uses less digits than its factorization.

644064435 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2044667 (or 2044664 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 36.

The square root of 644064435 is about 25378.4245964953. The cubic root of 644064435 is about 863.5943110507.

The spelling of 644064435 in words is "six hundred forty-four million, sixty-four thousand, four hundred thirty-five".