78828821 has 4 divisors (see below), whose sum is σ = 78907200. Its totient is φ = 78750444.

The previous prime is 78828811. The next prime is 78828851. The reversal of 78828821 is 12882887.

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: 12882887 = 31 ⋅415577.

It is a cyclic number.

It is not a de Polignac number, because 78828821 - 2²⁶ = 11719957 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 (78828811) 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, 37661 + ... + 39698.

It is an arithmetic number, because the mean of its divisors is an integer number (19726800).

Almost surely, 2^78828821 is an apocalyptic number.

It is an amenable number.

78828821 is a deficient number, since it is larger than the sum of its proper divisors (78379).

78828821 is a wasteful number, since it uses less digits than its factorization.

78828821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78378.

The product of its digits is 114688, while the sum is 44.

The square root of 78828821 is about 8878.5596241733. The cubic root of 78828821 is about 428.7739022280.

The spelling of 78828821 in words is "seventy-eight million, eight hundred twenty-eight thousand, eight hundred twenty-one".