78719821 has 8 divisors (see below), whose sum is σ = 79394040. Its totient is φ = 78048768.

The previous prime is 78719801. The next prime is 78719867. The reversal of 78719821 is 12891787.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 69538921 + 9180900 = 8339^2 + 3030^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 78719821 - 2⁹ = 78719309 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78719801) 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 7 ways as a sum of consecutive naturals, for example, 80085 + ... + 81061.

It is an arithmetic number, because the mean of its divisors is an integer number (9924255).

Almost surely, 2^78719821 is an apocalyptic number.

It is an amenable number.

78719821 is a deficient number, since it is larger than the sum of its proper divisors (674219).

78719821 is a wasteful number, since it uses less digits than its factorization.

78719821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1583.

The product of its digits is 56448, while the sum is 43.

The square root of 78719821 is about 8872.4191176928. The cubic root of 78719821 is about 428.5761830319.

The spelling of 78719821 in words is "seventy-eight million, seven hundred nineteen thousand, eight hundred twenty-one".