81559841 has 4 divisors (see below), whose sum is σ = 88974384. Its totient is φ = 74145300.

The previous prime is 81559813. The next prime is 81559843. The reversal of 81559841 is 14895518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81559841 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81559843) 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, 3707255 + ... + 3707276.

It is an arithmetic number, because the mean of its divisors is an integer number (22243596).

Almost surely, 2^81559841 is an apocalyptic number.

It is an amenable number.

81559841 is a deficient number, since it is larger than the sum of its proper divisors (7414543).

81559841 is a wasteful number, since it uses less digits than its factorization.

81559841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7414542.

The product of its digits is 57600, while the sum is 41.

The square root of 81559841 is about 9031.0487209404. The cubic root of 81559841 is about 433.6694110120.

The spelling of 81559841 in words is "eighty-one million, five hundred fifty-nine thousand, eight hundred forty-one".