81549169 has 8 divisors (see below), whose sum is σ = 88284672. Its totient is φ = 74879760.

The previous prime is 81549157. The next prime is 81549173. The reversal of 81549169 is 96194518.

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

It is a cyclic number.

It is not a de Polignac number, because 81549169 - 2⁹ = 81548657 is a prime.

It is a super-2 number, since 2×81549169² = 13300533929181122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81549869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13939 + ... + 18904.

It is an arithmetic number, because the mean of its divisors is an integer number (11035584).

Almost surely, 2^81549169 is an apocalyptic number.

It is an amenable number.

81549169 is a deficient number, since it is larger than the sum of its proper divisors (6735503).

81549169 is a wasteful number, since it uses less digits than its factorization.

81549169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33047.

The product of its digits is 77760, while the sum is 43.

The square root of 81549169 is about 9030.4578510727. The cubic root of 81549169 is about 433.6504951593.

It can be divided in two parts, 81549 and 169, that added together give a palindrome (81718).

The spelling of 81549169 in words is "eighty-one million, five hundred forty-nine thousand, one hundred sixty-nine".