81821169 has 12 divisors (see below), whose sum is σ = 119683200. Its totient is φ = 53856504.

The previous prime is 81821167. The next prime is 81821197. The reversal of 81821169 is 96112818.

It is not a de Polignac number, because 81821169 - 2¹ = 81821167 is a prime.

It is a super-2 number, since 2×81821169² = 13389407393053122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81821167) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 56829 + ... + 58250.

It is an arithmetic number, because the mean of its divisors is an integer number (9973600).

Almost surely, 2^81821169 is an apocalyptic number.

It is an amenable number.

81821169 is a deficient number, since it is larger than the sum of its proper divisors (37862031).

81821169 is a wasteful number, since it uses less digits than its factorization.

81821169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115164 (or 115161 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 81821169 is about 9045.5054585136. The cubic root of 81821169 is about 434.1320943306.

The spelling of 81821169 in words is "eighty-one million, eight hundred twenty-one thousand, one hundred sixty-nine".