8721961081 has 4 divisors (see below), whose sum is σ = 8723475072. Its totient is φ = 8720447092.

The previous prime is 8721961067. The next prime is 8721961103. The reversal of 8721961081 is 1801691278.

It is a happy number.

8721961081 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 8721961081 - 2¹⁹ = 8721436793 is a prime.

It is a super-2 number, since 2×8721961081² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8721961051) 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 3 ways as a sum of consecutive naturals, for example, 748321 + ... + 759886.

It is an arithmetic number, because the mean of its divisors is an integer number (2180868768).

Almost surely, 2^8721961081 is an apocalyptic number.

It is an amenable number.

8721961081 is a deficient number, since it is larger than the sum of its proper divisors (1513991).

8721961081 is a wasteful number, since it uses less digits than its factorization.

8721961081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1513990.

The product of its (nonzero) digits is 48384, while the sum is 43.

The square root of 8721961081 is about 93391.4400841962. The cubic root of 8721961081 is about 2058.4392206399.

The spelling of 8721961081 in words is "eight billion, seven hundred twenty-one million, nine hundred sixty-one thousand, eighty-one".