644438311629 has 8 divisors (see below), whose sum is σ = 982001236800. Its totient is φ = 368250463776.

The previous prime is 644438311619. The next prime is 644438311661. The reversal of 644438311629 is 926113834446.

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

It is not a de Polignac number, because 644438311629 - 2⁹ = 644438311117 is a prime.

It is a super-2 number, since 2×644438311629² (a number of 24 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644438311619) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15343769304 + ... + 15343769345.

It is an arithmetic number, because the mean of its divisors is an integer number (122750154600).

Almost surely, 2^644438311629 is an apocalyptic number.

It is an amenable number.

644438311629 is a deficient number, since it is larger than the sum of its proper divisors (337562925171).

644438311629 is a wasteful number, since it uses less digits than its factorization.

644438311629 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30687538659.

The product of its digits is 2985984, while the sum is 51.

The spelling of 644438311629 in words is "six hundred forty-four billion, four hundred thirty-eight million, three hundred eleven thousand, six hundred twenty-nine".