644045540543 has 2 divisors, whose sum is σ = 644045540544. Its totient is φ = 644045540542.

The previous prime is 644045540531. The next prime is 644045540581. The reversal of 644045540543 is 345045540446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644045540543 - 2³² = 639750573247 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 644045540494 and 644045540503.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644045540513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322022770271 + 322022770272.

It is an arithmetic number, because the mean of its divisors is an integer number (322022770272).

Almost surely, 2^644045540543 is an apocalyptic number.

644045540543 is a deficient number, since it is larger than the sum of its proper divisors (1).

644045540543 is an equidigital number, since it uses as much as digits as its factorization.

644045540543 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304000, while the sum is 44.

The spelling of 644045540543 in words is "six hundred forty-four billion, forty-five million, five hundred forty thousand, five hundred forty-three".