78999421 has 2 divisors, whose sum is σ = 78999422. Its totient is φ = 78999420.

The previous prime is 78999413. The next prime is 78999443. The reversal of 78999421 is 12499987.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65205625 + 13793796 = 8075^2 + 3714^2 .

It is an emirp because it is prime and its reverse (12499987) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78999421 - 2³ = 78999413 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78999721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39499710 + 39499711.

It is an arithmetic number, because the mean of its divisors is an integer number (39499711).

Almost surely, 2^78999421 is an apocalyptic number.

It is an amenable number.

78999421 is a deficient number, since it is larger than the sum of its proper divisors (1).

78999421 is an equidigital number, since it uses as much as digits as its factorization.

78999421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 49.

The square root of 78999421 is about 8888.1618459612. The cubic root of 78999421 is about 429.0829944314.

The spelling of 78999421 in words is "seventy-eight million, nine hundred ninety-nine thousand, four hundred twenty-one".