81022387139 has 4 divisors (see below), whose sum is σ = 83212181424. Its totient is φ = 78832592856.

The previous prime is 81022387091. The next prime is 81022387163. The reversal of 81022387139 is 93178322018.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81022387139 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 81022387139.

It is not an unprimeable number, because it can be changed into a prime (81022387939) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1094897087 + ... + 1094897160.

It is an arithmetic number, because the mean of its divisors is an integer number (20803045356).

Almost surely, 2^81022387139 is an apocalyptic number.

81022387139 is a deficient number, since it is larger than the sum of its proper divisors (2189794285).

81022387139 is a wasteful number, since it uses less digits than its factorization.

81022387139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2189794284.

The product of its (nonzero) digits is 145152, while the sum is 44.

The spelling of 81022387139 in words is "eighty-one billion, twenty-two million, three hundred eighty-seven thousand, one hundred thirty-nine".