81861099159 has 32 divisors (see below), whose sum is σ = 127367285760. Its totient is φ = 45803020032.

The previous prime is 81861099121. The next prime is 81861099179. The reversal of 81861099159 is 95199016818.

It is not a de Polignac number, because 81861099159 - 2²¹ = 81859002007 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81861099099 and 81861099108.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81861099179) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 20112 + ... + 405125.

It is an arithmetic number, because the mean of its divisors is an integer number (3980227680).

Almost surely, 2^81861099159 is an apocalyptic number.

81861099159 is a gapful number since it is divisible by the number (89) formed by its first and last digit.

81861099159 is a deficient number, since it is larger than the sum of its proper divisors (45506186601).

81861099159 is a wasteful number, since it uses less digits than its factorization.

81861099159 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 425439.

The product of its (nonzero) digits is 1399680, while the sum is 57.

The spelling of 81861099159 in words is "eighty-one billion, eight hundred sixty-one million, ninety-nine thousand, one hundred fifty-nine".