81930409 has 8 divisors (see below), whose sum is σ = 90894240. Its totient is φ = 73219200.

The previous prime is 81930403. The next prime is 81930449. The reversal of 81930409 is 90403918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81930409 - 2⁷ = 81930281 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81930403) 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 7 ways as a sum of consecutive naturals, for example, 62472 + ... + 63769.

It is an arithmetic number, because the mean of its divisors is an integer number (11361780).

Almost surely, 2^81930409 is an apocalyptic number.

It is an amenable number.

81930409 is a deficient number, since it is larger than the sum of its proper divisors (8963831).

81930409 is a wasteful number, since it uses less digits than its factorization.

81930409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126311.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 81930409 is about 9051.5418023672. The cubic root of 81930409 is about 434.3252126502.

The spelling of 81930409 in words is "eighty-one million, nine hundred thirty thousand, four hundred nine".