78420 has 24 divisors (see below), whose sum is σ = 219744. Its totient is φ = 20896.

The previous prime is 78401. The next prime is 78427. The reversal of 78420 is 2487.

78420 = T₁₃₆ + T₁₃₇ + ... + T₁₄₃.

It is a happy number.

It is a super-2 number, since 2×78420² = 12299392800, which contains 22 as substring.

It is a hoax number, since the sum of its digits (21) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78427) by changing a digit.

78420 is an untouchable number, because it is not equal to the sum of proper divisors of any 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, 594 + ... + 713.

It is an arithmetic number, because the mean of its divisors is an integer number (9156).

2⁷⁸⁴²⁰ is an apocalyptic number.

It is an amenable number.

78420 is an abundant number, since it is smaller than the sum of its proper divisors (141324).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109872).

78420 is a wasteful number, since it uses less digits than its factorization.

78420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1319 (or 1317 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 21.

The square root of 78420 is about 280.0357120083. The cubic root of 78420 is about 42.8031383264.

The spelling of 78420 in words is "seventy-eight thousand, four hundred twenty".