18644237617 has 2 divisors, whose sum is σ = 18644237618. Its totient is φ = 18644237616.

The previous prime is 18644237567. The next prime is 18644237639. The reversal of 18644237617 is 71673244681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18611507776 + 32729841 = 136424^2 + 5721^2 .

It is a cyclic number.

It is not a de Polignac number, because 18644237617 - 2¹⁵ = 18644204849 is a prime.

It is not a weakly prime, because it can be changed into another prime (18644237317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9322118808 + 9322118809.

It is an arithmetic number, because the mean of its divisors is an integer number (9322118809).

Almost surely, 2^18644237617 is an apocalyptic number.

It is an amenable number.

18644237617 is a deficient number, since it is larger than the sum of its proper divisors (1).

18644237617 is an equidigital number, since it uses as much as digits as its factorization.

18644237617 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1354752, while the sum is 49.

It can be divided in two parts, 1864 and 4237617, that added together give a square (4239481 = 2059²).

The spelling of 18644237617 in words is "eighteen billion, six hundred forty-four million, two hundred thirty-seven thousand, six hundred seventeen".