81920321 has 8 divisors (see below), whose sum is σ = 96643584. Its totient is φ = 67952160.

The previous prime is 81920309. The next prime is 81920327. The reversal of 81920321 is 12302918.

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 81920321 - 2¹⁰ = 81919297 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81920327) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 188540 + ... + 188973.

It is an arithmetic number, because the mean of its divisors is an integer number (12080448).

Almost surely, 2^81920321 is an apocalyptic number.

It is an amenable number.

81920321 is a deficient number, since it is larger than the sum of its proper divisors (14723263).

81920321 is a wasteful number, since it uses less digits than its factorization.

81920321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 377551.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 81920321 is about 9050.9845320827. The cubic root of 81920321 is about 434.3073859253.

The spelling of 81920321 in words is "eighty-one million, nine hundred twenty thousand, three hundred twenty-one".