81224136 has 48 divisors (see below), whose sum is σ = 251409600. Its totient is φ = 23206752.

The previous prime is 81224081. The next prime is 81224137. The reversal of 81224136 is 63142218.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (81224137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 80076 + ... + 81083.

It is an arithmetic number, because the mean of its divisors is an integer number (5237700).

Almost surely, 2^81224136 is an apocalyptic number.

It is an amenable number.

81224136 is an abundant number, since it is smaller than the sum of its proper divisors (170185464).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81224136 is a wasteful number, since it uses less digits than its factorization.

81224136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161178 (or 161171 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 81224136 is about 9012.4433978805. The cubic root of 81224136 is about 433.0735900326.

The spelling of 81224136 in words is "eighty-one million, two hundred twenty-four thousand, one hundred thirty-six".