18729719381 has 2 divisors, whose sum is σ = 18729719382. Its totient is φ = 18729719380.

The previous prime is 18729719341. The next prime is 18729719429. The reversal of 18729719381 is 18391792781.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11144180356 + 7585539025 = 105566^2 + 87095^2 .

It is an emirp because it is prime and its reverse (18391792781) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18729719381 is a prime.

It is a super-2 number, since 2×18729719381² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18729719311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9364859690 + 9364859691.

It is an arithmetic number, because the mean of its divisors is an integer number (9364859691).

Almost surely, 2^18729719381 is an apocalyptic number.

It is an amenable number.

18729719381 is a deficient number, since it is larger than the sum of its proper divisors (1).

18729719381 is an equidigital number, since it uses as much as digits as its factorization.

18729719381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1524096, while the sum is 56.

The spelling of 18729719381 in words is "eighteen billion, seven hundred twenty-nine million, seven hundred nineteen thousand, three hundred eighty-one".