78682721 has 4 divisors (see below), whose sum is σ = 84735252. Its totient is φ = 72630192.

The previous prime is 78682717. The next prime is 78682729. The reversal of 78682721 is 12728687.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12728687 = 61 ⋅208667.

It can be written as a sum of positive squares in 2 ways, for example, as 9610000 + 69072721 = 3100^2 + 8311^2 .

It is a cyclic number.

It is not a de Polignac number, because 78682721 - 2² = 78682717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78682729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3026246 + ... + 3026271.

It is an arithmetic number, because the mean of its divisors is an integer number (21183813).

Almost surely, 2^78682721 is an apocalyptic number.

It is an amenable number.

78682721 is a deficient number, since it is larger than the sum of its proper divisors (6052531).

78682721 is a wasteful number, since it uses less digits than its factorization.

78682721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6052530.

The product of its digits is 75264, while the sum is 41.

The square root of 78682721 is about 8870.3281224541. The cubic root of 78682721 is about 428.5088443163.

The spelling of 78682721 in words is "seventy-eight million, six hundred eighty-two thousand, seven hundred twenty-one".