644705379723 has 8 divisors (see below), whose sum is σ = 887336436736. Its totient is φ = 415938954600.

The previous prime is 644705379713. The next prime is 644705379749. The reversal of 644705379723 is 327973507446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 644705379723 - 2⁹ = 644705379211 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644705379713) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3466157863 + ... + 3466158048.

It is an arithmetic number, because the mean of its divisors is an integer number (110917054592).

Almost surely, 2^644705379723 is an apocalyptic number.

644705379723 is a deficient number, since it is larger than the sum of its proper divisors (242631057013).

644705379723 is a wasteful number, since it uses less digits than its factorization.

644705379723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6932315945.

The product of its (nonzero) digits is 26671680, while the sum is 57.

The spelling of 644705379723 in words is "six hundred forty-four billion, seven hundred five million, three hundred seventy-nine thousand, seven hundred twenty-three".