644426463 has 32 divisors (see below), whose sum is σ = 926069760. Its totient is φ = 397163520.

The previous prime is 644426437. The next prime is 644426473. The reversal of 644426463 is 364624446.

It is not a de Polignac number, because 644426463 - 2⁶ = 644426399 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644426413) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 1236643 + ... + 1237163.

It is an arithmetic number, because the mean of its divisors is an integer number (28939680).

Almost surely, 2^644426463 is an apocalyptic number.

644426463 is a deficient number, since it is larger than the sum of its proper divisors (281643297).

644426463 is a wasteful number, since it uses less digits than its factorization.

644426463 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 927.

The product of its digits is 331776, while the sum is 39.

The square root of 644426463 is about 25385.5561885100. The cubic root of 644426463 is about 863.7560892535.

The spelling of 644426463 in words is "six hundred forty-four million, four hundred twenty-six thousand, four hundred sixty-three".