78217680 has 160 divisors (see below), whose sum is σ = 270518400. Its totient is φ = 18579456.

The previous prime is 78217679. The next prime is 78217691. The reversal of 78217680 is 8671287.

It is a super-2 number, since 2×78217680² = 12236010929164800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 77016 + ... + 78024.

It is an arithmetic number, because the mean of its divisors is an integer number (1690740).

Almost surely, 2^78217680 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 78217680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (135259200).

78217680 is an abundant number, since it is smaller than the sum of its proper divisors (192300720).

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

78217680 is a wasteful number, since it uses less digits than its factorization.

78217680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1061 (or 1055 counting only the distinct ones).

The product of its (nonzero) digits is 37632, while the sum is 39.

The square root of 78217680 is about 8844.0759833914. The cubic root of 78217680 is about 427.6629658087.

The spelling of 78217680 in words is "seventy-eight million, two hundred seventeen thousand, six hundred eighty".