644378701 has 2 divisors, whose sum is σ = 644378702. Its totient is φ = 644378700.

The previous prime is 644378681. The next prime is 644378719. The reversal of 644378701 is 107873446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 543356100 + 101022601 = 23310^2 + 10051^2 .

It is a cyclic number.

It is not a de Polignac number, because 644378701 - 2²³ = 635990093 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644328701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322189350 + 322189351.

It is an arithmetic number, because the mean of its divisors is an integer number (322189351).

Almost surely, 2^644378701 is an apocalyptic number.

It is an amenable number.

644378701 is a deficient number, since it is larger than the sum of its proper divisors (1).

644378701 is an equidigital number, since it uses as much as digits as its factorization.

644378701 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 112896, while the sum is 40.

The square root of 644378701 is about 25384.6154392774. The cubic root of 644378701 is about 863.7347494834.

The spelling of 644378701 in words is "six hundred forty-four million, three hundred seventy-eight thousand, seven hundred one".