18618043787621 has 2 divisors, whose sum is σ = 18618043787622. Its totient is φ = 18618043787620.

The previous prime is 18618043787467. The next prime is 18618043787699. The reversal of 18618043787621 is 12678734081681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10730118770596 + 7887925017025 = 3275686^2 + 2808545^2 .

It is an emirp because it is prime and its reverse (12678734081681) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18618043787621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18618043784621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9309021893810 + 9309021893811.

It is an arithmetic number, because the mean of its divisors is an integer number (9309021893811).

Almost surely, 2^{18618043787621} is an apocalyptic number.

It is an amenable number.

18618043787621 is a deficient number, since it is larger than the sum of its proper divisors (1).

18618043787621 is an equidigital number, since it uses as much as digits as its factorization.

18618043787621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 21676032, while the sum is 62.

The spelling of 18618043787621 in words is "eighteen trillion, six hundred eighteen billion, forty-three million, seven hundred eighty-seven thousand, six hundred twenty-one".