78409520289 has 27 divisors (see below), whose sum is σ = 117642335187. Its totient is φ = 52257892608.

The previous prime is 78409520261. The next prime is 78409520297. The reversal of 78409520289 is 98202590487.

The square root of 78409520289 is 280017.

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

78409520289 is a `hidden beast` number, since 78 + 40 + 9 + 520 + 2 + 8 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1129968225 + 77279552064 = 33615^2 + 277992^2 .

It is a tau number, because it is divible by the number of its divisors (27).

It is not a de Polignac number, because 78409520289 - 2⁹ = 78409519777 is a prime.

It is a super-2 number, since 2×78409520289² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (78409520209) 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, 22679649 + ... + 22683105.

Almost surely, 2^78409520289 is an apocalyptic number.

78409520289 is the 280017-th square number.

78409520289 is the 140009-th centered octagonal number.

It is an amenable number.

78409520289 is a deficient number, since it is larger than the sum of its proper divisors (39232814898).

78409520289 is an frugal number, since it uses more digits than its factorization.

78409520289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6938 (or 3460 counting only the distinct ones).

The product of its (nonzero) digits is 2903040, while the sum is 54.

The spelling of 78409520289 in words is "seventy-eight billion, four hundred nine million, five hundred twenty thousand, two hundred eighty-nine".