78107721 has 8 divisors (see below), whose sum is σ = 104189184. Its totient is φ = 52049040.

The previous prime is 78107719. The next prime is 78107761. The reversal of 78107721 is 12770187.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 78107721 - 2¹ = 78107719 is a prime.

It is a super-2 number, since 2×78107721² = 12201632159627682, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (78107761) 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 7 ways as a sum of consecutive naturals, for example, 5391 + ... + 13611.

It is an arithmetic number, because the mean of its divisors is an integer number (13023648).

Almost surely, 2^78107721 is an apocalyptic number.

It is an amenable number.

78107721 is a deficient number, since it is larger than the sum of its proper divisors (26081463).

78107721 is a wasteful number, since it uses less digits than its factorization.

78107721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11391.

The product of its (nonzero) digits is 5488, while the sum is 33.

The square root of 78107721 is about 8837.8572629343. The cubic root of 78107721 is about 427.4624678927.

The spelling of 78107721 in words is "seventy-eight million, one hundred seven thousand, seven hundred twenty-one".