78440 has 32 divisors (see below), whose sum is σ = 184680. Its totient is φ = 29952.

The previous prime is 78439. The next prime is 78467. The reversal of 78440 is 4487.

It can be written as a sum of positive squares in 4 ways, for example, as 77284 + 1156 = 278^2 + 34^2 .

It is a plaindrome in base 7.

It is a zygodrome in base 7.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 1454 + ... + 1506.

2⁷⁸⁴⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 78440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (92340).

78440 is an abundant number, since it is smaller than the sum of its proper divisors (106240).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

78440 is a wasteful number, since it uses less digits than its factorization.

78440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101 (or 97 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 23.

The square root of 78440 is about 280.0714194630. The cubic root of 78440 is about 42.8067768115.

The spelling of 78440 in words is "seventy-eight thousand, four hundred forty".