78921 has 16 divisors (see below), whose sum is σ = 121600. Its totient is φ = 50544.

The previous prime is 78919. The next prime is 78929. The reversal of 78921 is 12987.

It is not a de Polignac number, because 78921 - 2¹ = 78919 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a plaindrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (78929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 960 + ... + 1038.

It is an arithmetic number, because the mean of its divisors is an integer number (7600).

2⁷⁸⁹²¹ is an apocalyptic number.

It is an amenable number.

78921 is a deficient number, since it is larger than the sum of its proper divisors (42679).

78921 is a wasteful number, since it uses less digits than its factorization.

78921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125 (or 119 counting only the distinct ones).

The product of its digits is 1008, while the sum is 27.

The square root of 78921 is about 280.9288166066. The cubic root of 78921 is about 42.8940966986.

It can be divided in two parts, 78 and 921, that added together give a palindrome (999).

The spelling of 78921 in words is "seventy-eight thousand, nine hundred twenty-one".