78665520 has 80 divisors (see below), whose sum is σ = 254483712. Its totient is φ = 20064000.

The previous prime is 78665471. The next prime is 78665549. The reversal of 78665520 is 2556687.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 1606 + ... + 12645.

Almost surely, 2^78665520 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 78665520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (127241856).

78665520 is an abundant number, since it is smaller than the sum of its proper divisors (175818192).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

78665520 is a wasteful number, since it uses less digits than its factorization.

78665520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14290 (or 14284 counting only the distinct ones).

The product of its (nonzero) digits is 100800, while the sum is 39.

The square root of 78665520 is about 8869.3584886394. The cubic root of 78665520 is about 428.4776162918.

The spelling of 78665520 in words is "seventy-eight million, six hundred sixty-five thousand, five hundred twenty".