8721820785 has 16 divisors (see below), whose sum is σ = 14251827456. Its totient is φ = 4552666368.

The previous prime is 8721820747. The next prime is 8721820787. The reversal of 8721820785 is 5870281278.

8721820785 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 8721820785 - 2²³ = 8713432177 is a prime.

It is not an unprimeable number, because it can be changed into a prime (8721820787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6184984 + ... + 6186393.

It is an arithmetic number, because the mean of its divisors is an integer number (890739216).

Almost surely, 2^8721820785 is an apocalyptic number.

It is an amenable number.

8721820785 is a deficient number, since it is larger than the sum of its proper divisors (5530006671).

8721820785 is a wasteful number, since it uses less digits than its factorization.

8721820785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12371432.

The product of its (nonzero) digits is 501760, while the sum is 48.

The square root of 8721820785 is about 93390.6889630867. The cubic root of 8721820785 is about 2058.4281836597.

The spelling of 8721820785 in words is "eight billion, seven hundred twenty-one million, eight hundred twenty thousand, seven hundred eighty-five".