644752628161 has 2 divisors, whose sum is σ = 644752628162. Its totient is φ = 644752628160.

The previous prime is 644752628129. The next prime is 644752628231. The reversal of 644752628161 is 161826257446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 579510697536 + 65241930625 = 761256^2 + 255425^2 .

It is a cyclic number.

It is not a de Polignac number, because 644752628161 - 2⁵ = 644752628129 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644752628099 and 644752628108.

It is not a weakly prime, because it can be changed into another prime (644752628761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322376314080 + 322376314081.

It is an arithmetic number, because the mean of its divisors is an integer number (322376314081).

Almost surely, 2^644752628161 is an apocalyptic number.

It is an amenable number.

644752628161 is a deficient number, since it is larger than the sum of its proper divisors (1).

644752628161 is an equidigital number, since it uses as much as digits as its factorization.

644752628161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3870720, while the sum is 52.

The spelling of 644752628161 in words is "six hundred forty-four billion, seven hundred fifty-two million, six hundred twenty-eight thousand, one hundred sixty-one".