81778530 has 32 divisors (see below), whose sum is σ = 197100288. Its totient is φ = 21715200.

The previous prime is 81778519. The next prime is 81778553. The reversal of 81778530 is 3587718.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 1575 + ... + 12885.

It is an arithmetic number, because the mean of its divisors is an integer number (6159384).

Almost surely, 2^81778530 is an apocalyptic number.

81778530 is an abundant number, since it is smaller than the sum of its proper divisors (115321758).

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

81778530 is a wasteful number, since it uses less digits than its factorization.

81778530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11562.

The product of its (nonzero) digits is 47040, while the sum is 39.

The square root of 81778530 is about 9043.1482349898. The cubic root of 81778530 is about 434.0566689648.

The spelling of 81778530 in words is "eighty-one million, seven hundred seventy-eight thousand, five hundred thirty".