644947141 has 2 divisors, whose sum is σ = 644947142. Its totient is φ = 644947140.

The previous prime is 644947129. The next prime is 644947181. The reversal of 644947141 is 141749446.

It is an a-pointer prime, because the next prime (644947181) can be obtained adding 644947141 to its sum of digits (40).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 591511041 + 53436100 = 24321^2 + 7310^2 .

It is a cyclic number.

It is not a de Polignac number, because 644947141 - 2⁵ = 644947109 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644947094 and 644947103.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644947181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322473570 + 322473571.

It is an arithmetic number, because the mean of its divisors is an integer number (322473571).

Almost surely, 2^644947141 is an apocalyptic number.

It is an amenable number.

644947141 is a deficient number, since it is larger than the sum of its proper divisors (1).

644947141 is an equidigital number, since it uses as much as digits as its factorization.

644947141 is an evil number, because the sum of its binary digits is even.

The product of its digits is 96768, while the sum is 40.

The square root of 644947141 is about 25395.8095165324. The cubic root of 644947141 is about 863.9886566333.

The spelling of 644947141 in words is "six hundred forty-four million, nine hundred forty-seven thousand, one hundred forty-one".