644240242042387 has 2 divisors, whose sum is σ = 644240242042388. Its totient is φ = 644240242042386.

The previous prime is 644240242042219. The next prime is 644240242042457. The reversal of 644240242042387 is 783240242042446.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644240242042387 is a prime.

It is not a weakly prime, because it can be changed into another prime (644240242042087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322120121021193 + 322120121021194.

It is an arithmetic number, because the mean of its divisors is an integer number (322120121021194).

Almost surely, 2^{644240242042387} is an apocalyptic number.

644240242042387 is a deficient number, since it is larger than the sum of its proper divisors (1).

644240242042387 is an equidigital number, since it uses as much as digits as its factorization.

644240242042387 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16515072, while the sum is 52.

The spelling of 644240242042387 in words is "six hundred forty-four trillion, two hundred forty billion, two hundred forty-two million, forty-two thousand, three hundred eighty-seven".