81636155 has 8 divisors (see below), whose sum is σ = 99343584. Its totient is φ = 64388800.

The previous prime is 81636143. The next prime is 81636157. The reversal of 81636155 is 55163618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81636155 - 2¹⁰ = 81635131 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81636157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 114626 + ... + 115335.

It is an arithmetic number, because the mean of its divisors is an integer number (12417948).

Almost surely, 2^81636155 is an apocalyptic number.

81636155 is a deficient number, since it is larger than the sum of its proper divisors (17707429).

81636155 is a wasteful number, since it uses less digits than its factorization.

81636155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 230037.

The product of its digits is 21600, while the sum is 35.

The square root of 81636155 is about 9035.2728237724. The cubic root of 81636155 is about 433.8046276017.

The spelling of 81636155 in words is "eighty-one million, six hundred thirty-six thousand, one hundred fifty-five".