78521017 has 4 divisors (see below), whose sum is σ = 78819840. Its totient is φ = 78222196.

The previous prime is 78520997. The next prime is 78521029. The reversal of 78521017 is 71012587.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 71012587 = 17 ⋅4177211.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78521017 is a prime.

It is a super-2 number, since 2×78521017² = 12331100221428578, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 78521017.

It is not an unprimeable number, because it can be changed into a prime (78521077) 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 3 ways as a sum of consecutive naturals, for example, 149017 + ... + 149542.

It is an arithmetic number, because the mean of its divisors is an integer number (19704960).

Almost surely, 2^78521017 is an apocalyptic number.

It is an amenable number.

78521017 is a deficient number, since it is larger than the sum of its proper divisors (298823).

78521017 is a wasteful number, since it uses less digits than its factorization.

78521017 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 298822.

The product of its (nonzero) digits is 3920, while the sum is 31.

The square root of 78521017 is about 8861.2085518850. The cubic root of 78521017 is about 428.2150944496.

The spelling of 78521017 in words is "seventy-eight million, five hundred twenty-one thousand, seventeen".