123978021281 has 2 divisors, whose sum is σ = 123978021282. Its totient is φ = 123978021280.

The previous prime is 123978021149. The next prime is 123978021289. The reversal of 123978021281 is 182120879321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 123541002256 + 437019025 = 351484^2 + 20905^2 .

It is an emirp because it is prime and its reverse (182120879321) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-123978021281 is a prime.

It is a super-2 number, since 2×123978021281² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (123978021289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61989010640 + 61989010641.

It is an arithmetic number, because the mean of its divisors is an integer number (61989010641).

Almost surely, 2^123978021281 is an apocalyptic number.

It is an amenable number.

123978021281 is a deficient number, since it is larger than the sum of its proper divisors (1).

123978021281 is an equidigital number, since it uses as much as digits as its factorization.

123978021281 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96768, while the sum is 44.

The spelling of 123978021281 in words is "one hundred twenty-three billion, nine hundred seventy-eight million, twenty-one thousand, two hundred eighty-one".