644880481 has 4 divisors (see below), whose sum is σ = 737006272. Its totient is φ = 552754692.

The previous prime is 644880479. The next prime is 644880517. The reversal of 644880481 is 184088446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 644880481 - 2¹ = 644880479 is a prime.

It is a super-2 number, since 2×644880481² = 831741669549582722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644880421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46062885 + ... + 46062898.

It is an arithmetic number, because the mean of its divisors is an integer number (184251568).

Almost surely, 2^644880481 is an apocalyptic number.

It is an amenable number.

644880481 is a deficient number, since it is larger than the sum of its proper divisors (92125791).

644880481 is an equidigital number, since it uses as much as digits as its factorization.

644880481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92125790.

The product of its (nonzero) digits is 196608, while the sum is 43.

The square root of 644880481 is about 25394.4970613714. The cubic root of 644880481 is about 863.9588890940.

The spelling of 644880481 in words is "six hundred forty-four million, eight hundred eighty thousand, four hundred eighty-one".