644164726645 has 16 divisors (see below), whose sum is σ = 843358511232. Its totient is φ = 468434368960.

The previous prime is 644164726643. The next prime is 644164726657. The reversal of 644164726645 is 546627461446.

It is not a de Polignac number, because 644164726645 - 2¹ = 644164726643 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (55).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644164726643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 79282 + ... + 1137811.

It is an arithmetic number, because the mean of its divisors is an integer number (52709906952).

Almost surely, 2^644164726645 is an apocalyptic number.

It is an amenable number.

644164726645 is a deficient number, since it is larger than the sum of its proper divisors (199193784587).

644164726645 is a wasteful number, since it uses less digits than its factorization.

644164726645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1226732.

The product of its digits is 23224320, while the sum is 55.

The spelling of 644164726645 in words is "six hundred forty-four billion, one hundred sixty-four million, seven hundred twenty-six thousand, six hundred forty-five".