644544445401 has 12 divisors (see below), whose sum is σ = 952660007728. Its totient is φ = 419703359544.

The previous prime is 644544445387. The next prime is 644544445421. The reversal of 644544445401 is 104544445446.

644544445401 is a `hidden beast` number, since 64 + 4 + 5 + 4 + 4 + 44 + 540 + 1 = 666.

It is not a de Polignac number, because 644544445401 - 2³⁷ = 507105491929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644544445421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 832744375 + ... + 832745148.

Almost surely, 2^644544445401 is an apocalyptic number.

It is an amenable number.

644544445401 is a deficient number, since it is larger than the sum of its proper divisors (308115562327).

644544445401 is a wasteful number, since it uses less digits than its factorization.

644544445401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1665489572 (or 1665489569 counting only the distinct ones).

The product of its (nonzero) digits is 2457600, while the sum is 45.

Adding to 644544445401 its sum of digits (45), we get a palindrome (644544445446).

The spelling of 644544445401 in words is "six hundred forty-four billion, five hundred forty-four million, four hundred forty-five thousand, four hundred one".