78311817 has 12 divisors (see below), whose sum is σ = 113614020. Its totient is φ = 51978528.

The previous prime is 78311791. The next prime is 78311833. The reversal of 78311817 is 71811387.

It can be written as a sum of positive squares in 2 ways, for example, as 74235456 + 4076361 = 8616^2 + 2019^2 .

It is not a de Polignac number, because 78311817 - 2¹⁴ = 78295433 is a prime.

It is a super-2 number, since 2×78311817² = 12265481363682978, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78311837) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16938 + ... + 21059.

It is an arithmetic number, because the mean of its divisors is an integer number (9467835).

Almost surely, 2^78311817 is an apocalyptic number.

It is an amenable number.

78311817 is a deficient number, since it is larger than the sum of its proper divisors (35302203).

78311817 is a wasteful number, since it uses less digits than its factorization.

78311817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38232 (or 38229 counting only the distinct ones).

The product of its digits is 9408, while the sum is 36.

The square root of 78311817 is about 8849.3964200956. The cubic root of 78311817 is about 427.8344648377.

The spelling of 78311817 in words is "seventy-eight million, three hundred eleven thousand, eight hundred seventeen".