81007321 has 2 divisors, whose sum is σ = 81007322. Its totient is φ = 81007320.

The previous prime is 81007307. The next prime is 81007351. The reversal of 81007321 is 12370018.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74304400 + 6702921 = 8620^2 + 2589^2 .

It is a cyclic number.

It is not a de Polignac number, because 81007321 - 2¹¹ = 81005273 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 81007292 and 81007301.

It is not a weakly prime, because it can be changed into another prime (81007351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40503660 + 40503661.

It is an arithmetic number, because the mean of its divisors is an integer number (40503661).

Almost surely, 2^81007321 is an apocalyptic number.

It is an amenable number.

81007321 is a deficient number, since it is larger than the sum of its proper divisors (1).

81007321 is an equidigital number, since it uses as much as digits as its factorization.

81007321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 81007321 is about 9000.4067130325. The cubic root of 81007321 is about 432.6879061429.

Adding to 81007321 its reverse (12370018), we get a palindrome (93377339).

The spelling of 81007321 in words is "eighty-one million, seven thousand, three hundred twenty-one".