81229536 has 144 divisors (see below), whose sum is σ = 250496064. Its totient is φ = 24870912.

The previous prime is 81229531. The next prime is 81229571. The reversal of 81229536 is 63592218.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 81229536.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81229531) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 229936 + ... + 230288.

It is an arithmetic number, because the mean of its divisors is an integer number (1739556).

Almost surely, 2^81229536 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81229536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (125248032).

81229536 is an abundant number, since it is smaller than the sum of its proper divisors (169266528).

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

81229536 is a wasteful number, since it uses less digits than its factorization.

81229536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 433 (or 422 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 81229536 is about 9012.7429786941. The cubic root of 81229536 is about 433.0831871207.

The spelling of 81229536 in words is "eighty-one million, two hundred twenty-nine thousand, five hundred thirty-six".