644362254020671 has 4 divisors (see below), whose sum is σ = 645314044647672. Its totient is φ = 643410463393672.

The previous prime is 644362254020669. The next prime is 644362254020687. The reversal of 644362254020671 is 176020452263446.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 644362254020671 - 2¹ = 644362254020669 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 (644362254020371) 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 3 ways as a sum of consecutive naturals, for example, 475895312485 + ... + 475895313838.

It is an arithmetic number, because the mean of its divisors is an integer number (161328511161918).

Almost surely, 2^{644362254020671} is an apocalyptic number.

644362254020671 is a deficient number, since it is larger than the sum of its proper divisors (951790627001).

644362254020671 is an equidigital number, since it uses as much as digits as its factorization.

644362254020671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 951790627000.

The product of its (nonzero) digits is 11612160, while the sum is 52.

The spelling of 644362254020671 in words is "six hundred forty-four trillion, three hundred sixty-two billion, two hundred fifty-four million, twenty thousand, six hundred seventy-one".