81139560 has 64 divisors (see below), whose sum is σ = 244054080. Its totient is φ = 21580800.

The previous prime is 81139559. The next prime is 81139567. The reversal of 81139560 is 6593118.

It is not an unprimeable number, because it can be changed into a prime (81139567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66960 + ... + 68160.

It is an arithmetic number, because the mean of its divisors is an integer number (3813345).

Almost surely, 2^81139560 is an apocalyptic number.

It is an amenable number.

81139560 is an abundant number, since it is smaller than the sum of its proper divisors (162914520).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81139560 is a wasteful number, since it uses less digits than its factorization.

81139560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1778 (or 1774 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 33.

The square root of 81139560 is about 9007.7499965308. The cubic root of 81139560 is about 432.9232227725.

The spelling of 81139560 in words is "eighty-one million, one hundred thirty-nine thousand, five hundred sixty".