81238189 has 12 divisors (see below), whose sum is σ = 86636628. Its totient is φ = 76160000.

The previous prime is 81238163. The next prime is 81238229. The reversal of 81238189 is 98183218.

It can be written as a sum of positive squares in 6 ways, for example, as 45118089 + 36120100 = 6717^2 + 6010^2 .

It is not a de Polignac number, because 81238189 - 2⁷ = 81238061 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81238109) 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, 115539 + ... + 116239.

It is an arithmetic number, because the mean of its divisors is an integer number (7219719).

Almost surely, 2^81238189 is an apocalyptic number.

It is an amenable number.

81238189 is a deficient number, since it is larger than the sum of its proper divisors (5398439).

81238189 is a wasteful number, since it uses less digits than its factorization.

81238189 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1136 (or 1119 counting only the distinct ones).

The product of its digits is 27648, while the sum is 40.

The square root of 81238189 is about 9013.2230084471. The cubic root of 81238189 is about 433.0985646789.

The spelling of 81238189 in words is "eighty-one million, two hundred thirty-eight thousand, one hundred eighty-nine".