18738246781 has 2 divisors, whose sum is σ = 18738246782. Its totient is φ = 18738246780.

The previous prime is 18738246773. The next prime is 18738246803. The reversal of 18738246781 is 18764283781.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15460684281 + 3277562500 = 124341^2 + 57250^2 .

It is a cyclic number.

It is not a de Polignac number, because 18738246781 - 2³ = 18738246773 is a prime.

It is a super-2 number, since 2×18738246781² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18738246281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9369123390 + 9369123391.

It is an arithmetic number, because the mean of its divisors is an integer number (9369123391).

Almost surely, 2^18738246781 is an apocalyptic number.

It is an amenable number.

18738246781 is a deficient number, since it is larger than the sum of its proper divisors (1).

18738246781 is an equidigital number, since it uses as much as digits as its factorization.

18738246781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3612672, while the sum is 55.

The spelling of 18738246781 in words is "eighteen billion, seven hundred thirty-eight million, two hundred forty-six thousand, seven hundred eighty-one".