81782784 has 240 divisors, whose sum is σ = 267567300. Its totient is φ = 24772608.

The previous prime is 81782759. The next prime is 81782803. The reversal of 81782784 is 48728718.

81782784 = 19³ + 20³ + ... + 134³.

It can be written as a sum of positive squares in 2 ways, for example, as 79709184 + 2073600 = 8928^2 + 1440^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2820082 + ... + 2820110.

Almost surely, 2^81782784 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 81782784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (133783650).

81782784 is an abundant number, since it is smaller than the sum of its proper divisors (185784516).

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

81782784 is a wasteful number, since it uses less digits than its factorization.

81782784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80 (or 51 counting only the distinct ones).

The product of its digits is 200704, while the sum is 45.

The square root of 81782784 is about 9043.3834376300. The cubic root of 81782784 is about 434.0641951662.

The spelling of 81782784 in words is "eighty-one million, seven hundred eighty-two thousand, seven hundred eighty-four".