644331103 has 4 divisors (see below), whose sum is σ = 693895048. Its totient is φ = 594767160.

The previous prime is 644331091. The next prime is 644331109. The reversal of 644331103 is 301133446.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 301133446 = 2 ⋅150566723.

It is not a de Polignac number, because 644331103 - 2²⁵ = 610776671 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644331109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24781953 + ... + 24781978.

It is an arithmetic number, because the mean of its divisors is an integer number (173473762).

Almost surely, 2^644331103 is an apocalyptic number.

644331103 is a deficient number, since it is larger than the sum of its proper divisors (49563945).

644331103 is a wasteful number, since it uses less digits than its factorization.

644331103 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49563944.

The product of its (nonzero) digits is 2592, while the sum is 25.

The square root of 644331103 is about 25383.6778856020. The cubic root of 644331103 is about 863.7134819385.

Adding to 644331103 its reverse (301133446), we get a palindrome (945464549).

It can be divided in two parts, 64433 and 1103, that added together give a 16-th power (65536 = 2¹⁶).

The spelling of 644331103 in words is "six hundred forty-four million, three hundred thirty-one thousand, one hundred three".