18743916781 has 2 divisors, whose sum is σ = 18743916782. Its totient is φ = 18743916780.

The previous prime is 18743916761. The next prime is 18743916791. The reversal of 18743916781 is 18761934781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16943187556 + 1800729225 = 130166^2 + 42435^2 .

It is a cyclic number.

It is not a de Polignac number, because 18743916781 - 2¹¹ = 18743914733 is a prime.

It is a super-2 number, since 2×18743916781² (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 (18743916701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9371958390 + 9371958391.

It is an arithmetic number, because the mean of its divisors is an integer number (9371958391).

Almost surely, 2^18743916781 is an apocalyptic number.

It is an amenable number.

18743916781 is a deficient number, since it is larger than the sum of its proper divisors (1).

18743916781 is an equidigital number, since it uses as much as digits as its factorization.

18743916781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2032128, while the sum is 55.

The spelling of 18743916781 in words is "eighteen billion, seven hundred forty-three million, nine hundred sixteen thousand, seven hundred eighty-one".