81947530 has 16 divisors (see below), whose sum is σ = 168577920. Its totient is φ = 28096272.

The previous prime is 81947527. The next prime is 81947543. The reversal of 81947530 is 3574918.

It is a self number, because there is not a number n which added to its sum of digits gives 81947530.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 585270 + ... + 585409.

It is an arithmetic number, because the mean of its divisors is an integer number (10536120).

Almost surely, 2^81947530 is an apocalyptic number.

81947530 is an abundant number, since it is smaller than the sum of its proper divisors (86630390).

81947530 is a wasteful number, since it uses less digits than its factorization.

81947530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1170693.

The product of its (nonzero) digits is 30240, while the sum is 37.

The square root of 81947530 is about 9052.4875034435. The cubic root of 81947530 is about 434.3554641939.

The spelling of 81947530 in words is "eighty-one million, nine hundred forty-seven thousand, five hundred thirty".