8139556721 has 8 divisors (see below), whose sum is σ = 8260726560. Its totient is φ = 8018648352.

The previous prime is 8139556681. The next prime is 8139556727. The reversal of 8139556721 is 1276559318.

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

It is a cyclic number.

It is not a de Polignac number, because 8139556721 - 2⁶ = 8139556657 is a prime.

It is a super-2 number, since 2×8139556721² (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 (8139556727) 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 7 ways as a sum of consecutive naturals, for example, 2195 + ... + 127608.

It is an arithmetic number, because the mean of its divisors is an integer number (1032590820).

Almost surely, 2^8139556721 is an apocalyptic number.

It is an amenable number.

8139556721 is a deficient number, since it is larger than the sum of its proper divisors (121169839).

8139556721 is a wasteful number, since it uses less digits than its factorization.

8139556721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130735.

The product of its digits is 453600, while the sum is 47.

The square root of 8139556721 is about 90219.4919127790. The cubic root of 8139556721 is about 2011.5627493383.

The spelling of 8139556721 in words is "eight billion, one hundred thirty-nine million, five hundred fifty-six thousand, seven hundred twenty-one".