82720321 has 2 divisors, whose sum is σ = 82720322. Its totient is φ = 82720320.

The previous prime is 82720291. The next prime is 82720327. The reversal of 82720321 is 12302728.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 82719025 + 1296 = 9095^2 + 36^2 .

It is a cyclic number.

It is not a de Polignac number, because 82720321 - 2⁷ = 82720193 is a prime.

It is not a weakly prime, because it can be changed into another prime (82720327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41360160 + 41360161.

It is an arithmetic number, because the mean of its divisors is an integer number (41360161).

Almost surely, 2^82720321 is an apocalyptic number.

It is an amenable number.

82720321 is a deficient number, since it is larger than the sum of its proper divisors (1).

82720321 is an equidigital number, since it uses as much as digits as its factorization.

82720321 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 82720321 is about 9095.0712476594. The cubic root of 82720321 is about 435.7165641631.

The spelling of 82720321 in words is "eighty-two million, seven hundred twenty thousand, three hundred twenty-one".