78354817 has 2 divisors, whose sum is σ = 78354818. Its totient is φ = 78354816.

The previous prime is 78354811. The next prime is 78354827. The reversal of 78354817 is 71845387.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62346816 + 16008001 = 7896^2 + 4001^2 .

It is an emirp because it is prime and its reverse (71845387) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78354817 is a prime.

It is a super-2 number, since 2×78354817² = 12278954694206978, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78354811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39177408 + 39177409.

It is an arithmetic number, because the mean of its divisors is an integer number (39177409).

Almost surely, 2^78354817 is an apocalyptic number.

It is an amenable number.

78354817 is a deficient number, since it is larger than the sum of its proper divisors (1).

78354817 is an equidigital number, since it uses as much as digits as its factorization.

78354817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 188160, while the sum is 43.

The square root of 78354817 is about 8851.8256309080. The cubic root of 78354817 is about 427.9127566229.

The spelling of 78354817 in words is "seventy-eight million, three hundred fifty-four thousand, eight hundred seventeen".