81189541 has 4 divisors (see below), whose sum is σ = 81638284. Its totient is φ = 80740800.

The previous prime is 81189509. The next prime is 81189583. The reversal of 81189541 is 14598118.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 28569025 + 52620516 = 5345^2 + 7254^2 .

It is a cyclic number.

It is not a de Polignac number, because 81189541 - 2⁵ = 81189509 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81189541.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81189041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 224100 + ... + 224461.

It is an arithmetic number, because the mean of its divisors is an integer number (20409571).

Almost surely, 2^81189541 is an apocalyptic number.

It is an amenable number.

81189541 is a deficient number, since it is larger than the sum of its proper divisors (448743).

81189541 is a wasteful number, since it uses less digits than its factorization.

81189541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 448742.

The product of its digits is 11520, while the sum is 37.

The square root of 81189541 is about 9010.5239026374. The cubic root of 81189541 is about 433.0120963717.

The spelling of 81189541 in words is "eighty-one million, one hundred eighty-nine thousand, five hundred forty-one".