81336424 has 32 divisors (see below), whose sum is σ = 166942440. Its totient is φ = 36921600.

The previous prime is 81336419. The next prime is 81336427. The reversal of 81336424 is 42463318.

It can be written as a sum of positive squares in 4 ways, for example, as 12744900 + 68591524 = 3570^2 + 8282^2 .

It is a super-2 number, since 2×81336424² = 13231227738215552, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (81336427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 67 + ... + 12754.

Almost surely, 2^81336424 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 81336424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (83471220).

81336424 is an abundant number, since it is smaller than the sum of its proper divisors (85606016).

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

81336424 is a wasteful number, since it uses less digits than its factorization.

81336424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12901 (or 12897 counting only the distinct ones).

The product of its digits is 13824, while the sum is 31.

The square root of 81336424 is about 9018.6708555086. The cubic root of 81336424 is about 433.2730651225.

The spelling of 81336424 in words is "eighty-one million, three hundred thirty-six thousand, four hundred twenty-four".