8005599981 has 16 divisors (see below), whose sum is σ = 11861603520. Its totient is φ = 5336411760.

The previous prime is 8005599961. The next prime is 8005599983. The reversal of 8005599981 is 1899955008.

8005599981 is a `hidden beast` number, since 8 + 0 + 0 + 559 + 9 + 9 + 81 = 666.

It is not a de Polignac number, because 8005599981 - 2¹⁰ = 8005598957 is a prime.

It is a super-2 number, since 2×8005599981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8005599983) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 320691 + ... + 344751.

It is an arithmetic number, because the mean of its divisors is an integer number (741350220).

Almost surely, 2^8005599981 is an apocalyptic number.

It is an amenable number.

8005599981 is a deficient number, since it is larger than the sum of its proper divisors (3856003539).

8005599981 is a wasteful number, since it uses less digits than its factorization.

8005599981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36393 (or 36387 counting only the distinct ones).

The product of its (nonzero) digits is 1166400, while the sum is 54.

The square root of 8005599981 is about 89474.0184690506. The cubic root of 8005599981 is about 2000.4665562375.

The spelling of 8005599981 in words is "eight billion, five million, five hundred ninety-nine thousand, nine hundred eighty-one".