81441561 has 8 divisors (see below), whose sum is σ = 109152160. Its totient is φ = 54012672.

The previous prime is 81441559. The next prime is 81441571. The reversal of 81441561 is 16514418.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81441561 - 2¹ = 81441559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81441571) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 69751 + ... + 70908.

It is an arithmetic number, because the mean of its divisors is an integer number (13644020).

Almost surely, 2^81441561 is an apocalyptic number.

It is an amenable number.

81441561 is a deficient number, since it is larger than the sum of its proper divisors (27710599).

81441561 is a wasteful number, since it uses less digits than its factorization.

81441561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140855.

The product of its digits is 3840, while the sum is 30.

The square root of 81441561 is about 9024.4978253640. The cubic root of 81441561 is about 433.4596703953.

Adding to 81441561 its reverse (16514418), we get a palindrome (97955979).

The spelling of 81441561 in words is "eighty-one million, four hundred forty-one thousand, five hundred sixty-one".