7918123781 has 2 divisors, whose sum is σ = 7918123782. Its totient is φ = 7918123780.

The previous prime is 7918123739. The next prime is 7918123789. The reversal of 7918123781 is 1873218197.

7918123781 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7291622881 + 626500900 = 85391^2 + 25030^2 .

It is a cyclic number.

It is not a de Polignac number, because 7918123781 - 2²² = 7913929477 is a prime.

It is a super-2 number, since 2×7918123781² (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 (7918123789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3959061890 + 3959061891.

It is an arithmetic number, because the mean of its divisors is an integer number (3959061891).

Almost surely, 2^7918123781 is an apocalyptic number.

It is an amenable number.

7918123781 is a deficient number, since it is larger than the sum of its proper divisors (1).

7918123781 is an equidigital number, since it uses as much as digits as its factorization.

7918123781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 169344, while the sum is 47.

The square root of 7918123781 is about 88983.8399991819. The cubic root of 7918123781 is about 1993.1535717028.

The spelling of 7918123781 in words is "seven billion, nine hundred eighteen million, one hundred twenty-three thousand, seven hundred eighty-one".