81661084 has 12 divisors (see below), whose sum is σ = 142970184. Its totient is φ = 40812464.

The previous prime is 81661067. The next prime is 81661087. The reversal of 81661084 is 48016618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81661087) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 15267 + ... + 19909.

It is an arithmetic number, because the mean of its divisors is an integer number (11914182).

Almost surely, 2^81661084 is an apocalyptic number.

It is an amenable number.

81661084 is a deficient number, since it is larger than the sum of its proper divisors (61309100).

81661084 is a wasteful number, since it uses less digits than its factorization.

81661084 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9044 (or 9042 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 34.

The square root of 81661084 is about 9036.6522562285. The cubic root of 81661084 is about 433.8487796687.

The spelling of 81661084 in words is "eighty-one million, six hundred sixty-one thousand, eighty-four".