81408641 has 4 divisors (see below), whose sum is σ = 82389552. Its totient is φ = 80427732.

The previous prime is 81408623. The next prime is 81408643. The reversal of 81408641 is 14680418.

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 81408641 - 2⁶ = 81408577 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81408598 and 81408607.

It is not an unprimeable number, because it can be changed into a prime (81408643) 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, 490331 + ... + 490496.

It is an arithmetic number, because the mean of its divisors is an integer number (20597388).

Almost surely, 2^81408641 is an apocalyptic number.

It is an amenable number.

81408641 is a deficient number, since it is larger than the sum of its proper divisors (980911).

81408641 is an equidigital number, since it uses as much as digits as its factorization.

81408641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 980910.

The product of its (nonzero) digits is 6144, while the sum is 32.

The square root of 81408641 is about 9022.6737168092. The cubic root of 81408641 is about 433.4012587143.

The spelling of 81408641 in words is "eighty-one million, four hundred eight thousand, six hundred forty-one".