78028321 has 4 divisors (see below), whose sum is σ = 89175232. Its totient is φ = 66881412.

The previous prime is 78028309. The next prime is 78028331. The reversal of 78028321 is 12382087.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12382087 = 37 ⋅334651.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78028321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78028331) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5573445 + ... + 5573458.

It is an arithmetic number, because the mean of its divisors is an integer number (22293808).

Almost surely, 2^78028321 is an apocalyptic number.

It is an amenable number.

78028321 is a deficient number, since it is larger than the sum of its proper divisors (11146911).

78028321 is a wasteful number, since it uses less digits than its factorization.

78028321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11146910.

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 78028321 is about 8833.3640817075. The cubic root of 78028321 is about 427.3175738639.

The spelling of 78028321 in words is "seventy-eight million, twenty-eight thousand, three hundred twenty-one".