81780336 has 120 divisors (see below), whose sum is σ = 264451824. Its totient is φ = 23316480.

The previous prime is 81780331. The next prime is 81780359. The reversal of 81780336 is 63308718.

81780336 = 83² + 84² + ... + 626².

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 81780336.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81780331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 25410 + ... + 28446.

Almost surely, 2^81780336 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 81780336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132225912).

81780336 is an abundant number, since it is smaller than the sum of its proper divisors (182671488).

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

81780336 is a wasteful number, since it uses less digits than its factorization.

81780336 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3079 (or 3070 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 81780336 is about 9043.2480890441. The cubic root of 81780336 is about 434.0598641823.

The spelling of 81780336 in words is "eighty-one million, seven hundred eighty thousand, three hundred thirty-six".