644338801 has 4 divisors (see below), whose sum is σ = 644462500. Its totient is φ = 644215104.

The previous prime is 644338787. The next prime is 644338817. The reversal of 644338801 is 108833446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 108833446 = 2 ⋅54416723.

It can be written as a sum of positive squares in 2 ways, for example, as 96825600 + 547513201 = 9840^2 + 23399^2 .

It is a cyclic number.

It is not a de Polignac number, because 644338801 - 2¹¹ = 644336753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644335801) 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, 53676 + ... + 64573.

It is an arithmetic number, because the mean of its divisors is an integer number (161115625).

Almost surely, 2^644338801 is an apocalyptic number.

It is an amenable number.

644338801 is a deficient number, since it is larger than the sum of its proper divisors (123699).

644338801 is a wasteful number, since it uses less digits than its factorization.

644338801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123698.

The product of its (nonzero) digits is 55296, while the sum is 37.

The square root of 644338801 is about 25383.8295180219. The cubic root of 644338801 is about 863.7169215986.

The spelling of 644338801 in words is "six hundred forty-four million, three hundred thirty-eight thousand, eight hundred one".