78661547 has 4 divisors (see below), whose sum is σ = 78690456. Its totient is φ = 78632640.

The previous prime is 78661523. The next prime is 78661559. The reversal of 78661547 is 74516687.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74516687 = 7 ⋅10645241.

It is a cyclic number.

It is not a de Polignac number, because 78661547 - 2¹² = 78657451 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 78661498 and 78661507.

It is not an unprimeable number, because it can be changed into a prime (78601547) 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 3 ways as a sum of consecutive naturals, for example, 9893 + ... + 15974.

It is an arithmetic number, because the mean of its divisors is an integer number (19672614).

Almost surely, 2^78661547 is an apocalyptic number.

78661547 is a deficient number, since it is larger than the sum of its proper divisors (28909).

78661547 is a wasteful number, since it uses less digits than its factorization.

78661547 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28908.

The product of its digits is 282240, while the sum is 44.

The square root of 78661547 is about 8869.1345124539. The cubic root of 78661547 is about 428.4704027535.

The spelling of 78661547 in words is "seventy-eight million, six hundred sixty-one thousand, five hundred forty-seven".