78728549 has 2 divisors, whose sum is σ = 78728550. Its totient is φ = 78728548.

The previous prime is 78728539. The next prime is 78728593. The reversal of 78728549 is 94582787.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 75777025 + 2951524 = 8705^2 + 1718^2 .

It is a cyclic number.

It is not a de Polignac number, because 78728549 - 2¹² = 78724453 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 78728497 and 78728506.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78728509) 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 as a sum of consecutive naturals, namely, 39364274 + 39364275.

It is an arithmetic number, because the mean of its divisors is an integer number (39364275).

Almost surely, 2^78728549 is an apocalyptic number.

It is an amenable number.

78728549 is a deficient number, since it is larger than the sum of its proper divisors (1).

78728549 is an equidigital number, since it uses as much as digits as its factorization.

78728549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1128960, while the sum is 50.

The square root of 78728549 is about 8872.9109654048. The cubic root of 78728549 is about 428.5920217988.

The spelling of 78728549 in words is "seventy-eight million, seven hundred twenty-eight thousand, five hundred forty-nine".