78406420 has 24 divisors (see below), whose sum is σ = 165156264. Its totient is φ = 31266816.

The previous prime is 78406417. The next prime is 78406421. The reversal of 78406420 is 2460487.

It can be written as a sum of positive squares in 4 ways, for example, as 6563844 + 71842576 = 2562^2 + 8476^2 .

It is a super-2 number, since 2×78406420² = 12295133394432800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78406421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 924 + ... + 12556.

It is an arithmetic number, because the mean of its divisors is an integer number (6881511).

Almost surely, 2^78406420 is an apocalyptic number.

It is an amenable number.

78406420 is an abundant number, since it is smaller than the sum of its proper divisors (86749844).

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

78406420 is a wasteful number, since it uses less digits than its factorization.

78406420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11979 (or 11977 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 31.

The square root of 78406420 is about 8854.7399735961. The cubic root of 78406420 is about 428.0066744235.

The spelling of 78406420 in words is "seventy-eight million, four hundred six thousand, four hundred twenty".