78759221 has 4 divisors (see below), whose sum is σ = 79159212. Its totient is φ = 78359232.

The previous prime is 78759217. The next prime is 78759223. The reversal of 78759221 is 12295787.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12295787 = 7 ⋅1756541.

It can be written as a sum of positive squares in 2 ways, for example, as 74200996 + 4558225 = 8614^2 + 2135^2 .

It is a cyclic number.

It is not a de Polignac number, because 78759221 - 2² = 78759217 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78759223) 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, 199700 + ... + 200093.

It is an arithmetic number, because the mean of its divisors is an integer number (19789803).

Almost surely, 2^78759221 is an apocalyptic number.

It is an amenable number.

78759221 is a deficient number, since it is larger than the sum of its proper divisors (399991).

78759221 is a wasteful number, since it uses less digits than its factorization.

78759221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399990.

The product of its digits is 70560, while the sum is 41.

The square root of 78759221 is about 8874.6392039339. The cubic root of 78759221 is about 428.6476732233.

The spelling of 78759221 in words is "seventy-eight million, seven hundred fifty-nine thousand, two hundred twenty-one".