8207920721 has 64 divisors (see below), whose sum is σ = 11444267520. Its totient is φ = 5678346240.

The previous prime is 8207920709. The next prime is 8207920727. The reversal of 8207920721 is 1270297028.

8207920721 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 8207920721 - 2⁶ = 8207920657 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (8207920727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 12569231 + ... + 12569883.

It is an arithmetic number, because the mean of its divisors is an integer number (178816680).

Almost surely, 2^8207920721 is an apocalyptic number.

It is an amenable number.

8207920721 is a deficient number, since it is larger than the sum of its proper divisors (3236346799).

8207920721 is a wasteful number, since it uses less digits than its factorization.

8207920721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1146.

The product of its (nonzero) digits is 28224, while the sum is 38.

The square root of 8207920721 is about 90597.5756905228. The cubic root of 8207920721 is about 2017.1787495641.

The spelling of 8207920721 in words is "eight billion, two hundred seven million, nine hundred twenty thousand, seven hundred twenty-one".