81360139 has 6 divisors (see below), whose sum is σ = 94643484. Its totient is φ = 69737220.

The previous prime is 81360127. The next prime is 81360161. The reversal of 81360139 is 93106318.

It is not a de Polignac number, because 81360139 - 2⁹ = 81359627 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81360139.

It is not an unprimeable number, because it can be changed into a prime (81360119) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 830157 + ... + 830254.

It is an arithmetic number, because the mean of its divisors is an integer number (15773914).

Almost surely, 2^81360139 is an apocalyptic number.

81360139 is a deficient number, since it is larger than the sum of its proper divisors (13283345).

81360139 is a wasteful number, since it uses less digits than its factorization.

81360139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1660425 (or 1660418 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 81360139 is about 9019.9855321392. The cubic root of 81360139 is about 433.3151703761.

The spelling of 81360139 in words is "eighty-one million, three hundred sixty thousand, one hundred thirty-nine".