644576451377 has 2 divisors, whose sum is σ = 644576451378. Its totient is φ = 644576451376.

The previous prime is 644576451359. The next prime is 644576451403. The reversal of 644576451377 is 773154675446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 580170132721 + 64406318656 = 761689^2 + 253784^2 .

It is a cyclic number.

It is not a de Polignac number, because 644576451377 - 2⁶ = 644576451313 is a prime.

It is a super-2 number, since 2×644576451377² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (644576451347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322288225688 + 322288225689.

It is an arithmetic number, because the mean of its divisors is an integer number (322288225689).

Almost surely, 2^644576451377 is an apocalyptic number.

It is an amenable number.

644576451377 is a deficient number, since it is larger than the sum of its proper divisors (1).

644576451377 is an equidigital number, since it uses as much as digits as its factorization.

644576451377 is an evil number, because the sum of its binary digits is even.

The product of its digits is 59270400, while the sum is 59.

The spelling of 644576451377 in words is "six hundred forty-four billion, five hundred seventy-six million, four hundred fifty-one thousand, three hundred seventy-seven".