1278398499841 has 4 divisors (see below), whose sum is σ = 1295910808132. Its totient is φ = 1260886191552.

The previous prime is 1278398499823. The next prime is 1278398499857. The reversal of 1278398499841 is 1489948938721.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 787249827441 + 491148672400 = 887271^2 + 700820^2 .

It is a cyclic number.

It is not a de Polignac number, because 1278398499841 - 2¹⁷ = 1278398368769 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (73), and also a Moran number because the ratio is a prime number: 17512308217 = 1278398499841 / (1 + 2 + 7 + 8 + 3 + 9 + 8 + 4 + 9 + 9 + 8 + 4 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1278398499941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8756154036 + ... + 8756154181.

It is an arithmetic number, because the mean of its divisors is an integer number (323977702033).

Almost surely, 2^{1278398499841} is an apocalyptic number.

It is an amenable number.

1278398499841 is a deficient number, since it is larger than the sum of its proper divisors (17512308291).

1278398499841 is an equidigital number, since it uses as much as digits as its factorization.

1278398499841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17512308290.

The product of its digits is 250822656, while the sum is 73.

The spelling of 1278398499841 in words is "one trillion, two hundred seventy-eight billion, three hundred ninety-eight million, four hundred ninety-nine thousand, eight hundred forty-one".