78442817 has 2 divisors, whose sum is σ = 78442818. Its totient is φ = 78442816.

The previous prime is 78442783. The next prime is 78442823. The reversal of 78442817 is 71824487.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76457536 + 1985281 = 8744^2 + 1409^2 .

It is a cyclic number.

It is not a de Polignac number, because 78442817 - 2⁶ = 78442753 is a prime.

It is a plaindrome in base 13.

It is not a weakly prime, because it can be changed into another prime (78442517) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39221408 + 39221409.

It is an arithmetic number, because the mean of its divisors is an integer number (39221409).

Almost surely, 2^78442817 is an apocalyptic number.

It is an amenable number.

78442817 is a deficient number, since it is larger than the sum of its proper divisors (1).

78442817 is an equidigital number, since it uses as much as digits as its factorization.

78442817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 100352, while the sum is 41.

The square root of 78442817 is about 8856.7949620616. The cubic root of 78442817 is about 428.0728924239.

The spelling of 78442817 in words is "seventy-eight million, four hundred forty-two thousand, eight hundred seventeen".