78521816 has 32 divisors (see below), whose sum is σ = 154103040. Its totient is φ = 37438368.

The previous prime is 78521809. The next prime is 78521837. The reversal of 78521816 is 61812587.

It is an alternating number because its digits alternate between odd and even.

It is a self number, because there is not a number n which added to its sum of digits gives 78521816.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 107645 + ... + 108371.

It is an arithmetic number, because the mean of its divisors is an integer number (4815720).

Almost surely, 2^78521816 is an apocalyptic number.

It is an amenable number.

78521816 is a deficient number, since it is larger than the sum of its proper divisors (75581224).

78521816 is a wasteful number, since it uses less digits than its factorization.

78521816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1343 (or 1339 counting only the distinct ones).

The product of its digits is 26880, while the sum is 38.

The square root of 78521816 is about 8861.2536359141. The cubic root of 78521816 is about 428.2165468960.

The spelling of 78521816 in words is "seventy-eight million, five hundred twenty-one thousand, eight hundred sixteen".