78803521 has 4 divisors (see below), whose sum is σ = 80095444. Its totient is φ = 77511600.

The previous prime is 78803503. The next prime is 78803561. The reversal of 78803521 is 12530887.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12530887 = 17 ⋅737111.

It can be written as a sum of positive squares in 2 ways, for example, as 4223025 + 74580496 = 2055^2 + 8636^2 .

It is a cyclic number.

It is not a de Polignac number, because 78803521 - 2⁵ = 78803489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78803561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 645870 + ... + 645991.

It is an arithmetic number, because the mean of its divisors is an integer number (20023861).

Almost surely, 2^78803521 is an apocalyptic number.

It is an amenable number.

78803521 is a deficient number, since it is larger than the sum of its proper divisors (1291923).

78803521 is a wasteful number, since it uses less digits than its factorization.

78803521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1291922.

The product of its (nonzero) digits is 13440, while the sum is 34.

The square root of 78803521 is about 8877.1347291792. The cubic root of 78803521 is about 428.7280258580.

The spelling of 78803521 in words is "seventy-eight million, eight hundred three thousand, five hundred twenty-one".