78000421 has 2 divisors, whose sum is σ = 78000422. Its totient is φ = 78000420.

The previous prime is 78000407. The next prime is 78000443. The reversal of 78000421 is 12400087.

It is an a-pointer prime, because the next prime (78000443) can be obtained adding 78000421 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72760900 + 5239521 = 8530^2 + 2289^2 .

It is a cyclic number.

It is not a de Polignac number, because 78000421 - 2¹⁵ = 77967653 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 78000392 and 78000401.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78000451) 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 as a sum of consecutive naturals, namely, 39000210 + 39000211.

It is an arithmetic number, because the mean of its divisors is an integer number (39000211).

Almost surely, 2^78000421 is an apocalyptic number.

It is an amenable number.

78000421 is a deficient number, since it is larger than the sum of its proper divisors (1).

78000421 is an equidigital number, since it uses as much as digits as its factorization.

78000421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 78000421 is about 8831.7847007273. The cubic root of 78000421 is about 427.2666368818.

The spelling of 78000421 in words is "seventy-eight million, four hundred twenty-one", and thus it is an aban number.