1309978678849 has 27 divisors (see below), whose sum is σ = 1381448880201. Its totient is φ = 1242149627040.

The previous prime is 1309978678843. The next prime is 1309978678861. The reversal of 1309978678849 is 9488768799031.

The square root of 1309978678849 is 1144543.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 393057525249 + 916921153600 = 626943^2 + 957560^2 .

It is not a de Polignac number, because 1309978678849 - 2¹³ = 1309978670657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1309978678843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 2024696244 + ... + 2024696890.

Almost surely, 2^{1309978678849} is an apocalyptic number.

1309978678849 is the 1144543-rd square number.

1309978678849 is the 572272-nd centered octagonal number.

It is an amenable number.

1309978678849 is a deficient number, since it is larger than the sum of its proper divisors (71470201352).

1309978678849 is an frugal number, since it uses more digits than its factorization.

1309978678849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1474 (or 737 counting only the distinct ones).

The product of its (nonzero) digits is 1316818944, while the sum is 79.

The spelling of 1309978678849 in words is "one trillion, three hundred nine billion, nine hundred seventy-eight million, six hundred seventy-eight thousand, eight hundred forty-nine".