644642646611137 has 2 divisors, whose sum is σ = 644642646611138. Its totient is φ = 644642646611136.

The previous prime is 644642646611123. The next prime is 644642646611177. The reversal of 644642646611137 is 731116646246446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 567427130091441 + 77215516519696 = 23820729^2 + 8787236^2 .

It is a cyclic number.

It is not a de Polignac number, because 644642646611137 - 2²⁷ = 644642512393409 is a prime.

It is a super-2 number, since 2×644642646611137² (a number of 30 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (644642646611177) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322321323305568 + 322321323305569.

It is an arithmetic number, because the mean of its divisors is an integer number (322321323305569).

Almost surely, 2^{644642646611137} is an apocalyptic number.

It is an amenable number.

644642646611137 is a deficient number, since it is larger than the sum of its proper divisors (1).

644642646611137 is an equidigital number, since it uses as much as digits as its factorization.

644642646611137 is an evil number, because the sum of its binary digits is even.

The product of its digits is 83607552, while the sum is 61.

The spelling of 644642646611137 in words is "six hundred forty-four trillion, six hundred forty-two billion, six hundred forty-six million, six hundred eleven thousand, one hundred thirty-seven".