78431821 has 8 divisors (see below), whose sum is σ = 84661920. Its totient is φ = 72229872.

The previous prime is 78431819. The next prime is 78431833. The reversal of 78431821 is 12813487.

It is a happy number.

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

It is not a de Polignac number, because 78431821 - 2¹ = 78431819 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 (78431621) 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, 1051 + ... + 12568.

It is an arithmetic number, because the mean of its divisors is an integer number (10582740).

Almost surely, 2^78431821 is an apocalyptic number.

It is an amenable number.

78431821 is a deficient number, since it is larger than the sum of its proper divisors (6230099).

78431821 is a wasteful number, since it uses less digits than its factorization.

78431821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14075.

The product of its digits is 10752, while the sum is 34.

The square root of 78431821 is about 8856.1741739873. The cubic root of 78431821 is about 428.0528892774.

The spelling of 78431821 in words is "seventy-eight million, four hundred thirty-one thousand, eight hundred twenty-one".