81840433 has 4 divisors (see below), whose sum is σ = 83062000. Its totient is φ = 80618868.

The previous prime is 81840413. The next prime is 81840439. The reversal of 81840433 is 33404818.

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, and also an emirpimes, since its reverse is a distinct semiprime: 33404818 = 2 ⋅16702409.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81840433 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81840395 and 81840404.

It is not an unprimeable number, because it can be changed into a prime (81840439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 610683 + ... + 610816.

It is an arithmetic number, because the mean of its divisors is an integer number (20765500).

Almost surely, 2^81840433 is an apocalyptic number.

It is an amenable number.

81840433 is a deficient number, since it is larger than the sum of its proper divisors (1221567).

81840433 is a wasteful number, since it uses less digits than its factorization.

81840433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1221566.

The product of its (nonzero) digits is 9216, while the sum is 31.

The square root of 81840433 is about 9046.5702340721. The cubic root of 81840433 is about 434.1661623862.

The spelling of 81840433 in words is "eighty-one million, eight hundred forty thousand, four hundred thirty-three".