8721508581 has 12 divisors (see below), whose sum is σ = 12600290560. Its totient is φ = 5813159400.

The previous prime is 8721508559. The next prime is 8721508619. The reversal of 8721508581 is 1858051278.

It is not a de Polignac number, because 8721508581 - 2¹¹ = 8721506533 is a prime.

It is a super-2 number, since 2×8721508581² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8721508501) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 50245 + ... + 141306.

Almost surely, 2^8721508581 is an apocalyptic number.

It is an amenable number.

8721508581 is a deficient number, since it is larger than the sum of its proper divisors (3878781979).

8721508581 is a wasteful number, since it uses less digits than its factorization.

8721508581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196616 (or 196613 counting only the distinct ones).

The product of its (nonzero) digits is 179200, while the sum is 45.

The square root of 8721508581 is about 93389.0174538741. The cubic root of 8721508581 is about 2058.4036223822.

It can be divided in two parts, 872 and 1508581, that added together give a triangular number (1509453 = T₁₇₃₇).

The spelling of 8721508581 in words is "eight billion, seven hundred twenty-one million, five hundred eight thousand, five hundred eighty-one".