81660043 has 4 divisors (see below), whose sum is σ = 85957960. Its totient is φ = 77362128.

The previous prime is 81660031. The next prime is 81660049. The reversal of 81660043 is 34006618.

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

It is a cyclic number.

It is not a de Polignac number, because 81660043 - 2⁹ = 81659531 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81659993 and 81660020.

It is not an unprimeable number, because it can be changed into a prime (81660049) 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, 2148930 + ... + 2148967.

It is an arithmetic number, because the mean of its divisors is an integer number (21489490).

Almost surely, 2^81660043 is an apocalyptic number.

81660043 is a deficient number, since it is larger than the sum of its proper divisors (4297917).

81660043 is a wasteful number, since it uses less digits than its factorization.

81660043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4297916.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 81660043 is about 9036.5946572810. The cubic root of 81660043 is about 433.8469361203.

The spelling of 81660043 in words is "eighty-one million, six hundred sixty thousand, forty-three".