81423841 has 4 divisors (see below), whose sum is σ = 84964032. Its totient is φ = 77883652.

The previous prime is 81423833. The next prime is 81423857. The reversal of 81423841 is 14832418.

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 not a de Polignac number, because 81423841 - 2³ = 81423833 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81423871) 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, 1770061 + ... + 1770106.

It is an arithmetic number, because the mean of its divisors is an integer number (21241008).

Almost surely, 2^81423841 is an apocalyptic number.

It is an amenable number.

81423841 is a deficient number, since it is larger than the sum of its proper divisors (3540191).

81423841 is a wasteful number, since it uses less digits than its factorization.

81423841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3540190.

The product of its digits is 6144, while the sum is 31.

The square root of 81423841 is about 9023.5159998750. The cubic root of 81423841 is about 433.4282308273.

The spelling of 81423841 in words is "eighty-one million, four hundred twenty-three thousand, eight hundred forty-one".