81520336 has 40 divisors (see below), whose sum is σ = 167127200. Its totient is φ = 38413440.

The previous prime is 81520333. The next prime is 81520367. The reversal of 81520336 is 63302518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81520331) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 69031 + ... + 70201.

It is an arithmetic number, because the mean of its divisors is an integer number (4178180).

Almost surely, 2^81520336 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 81520336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (83563600).

81520336 is an abundant number, since it is smaller than the sum of its proper divisors (85606864).

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

81520336 is a wasteful number, since it uses less digits than its factorization.

81520336 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1427 (or 1421 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 81520336 is about 9028.8612792533. The cubic root of 81520336 is about 433.5993811350.

The spelling of 81520336 in words is "eighty-one million, five hundred twenty thousand, three hundred thirty-six".