8130721 has 2 divisors, whose sum is σ = 8130722. Its totient is φ = 8130720.

The previous prime is 8130697. The next prime is 8130737. The reversal of 8130721 is 1270318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6964321 + 1166400 = 2639^2 + 1080^2 .

It is a cyclic number.

It is not a de Polignac number, because 8130721 - 2⁷ = 8130593 is a prime.

It is a super-2 number, since 2×8130721² = 132217247959682, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 8130692 and 8130701.

It is not a weakly prime, because it can be changed into another prime (8130761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4065360 + 4065361.

It is an arithmetic number, because the mean of its divisors is an integer number (4065361).

Almost surely, 2^8130721 is an apocalyptic number.

It is an amenable number.

8130721 is a deficient number, since it is larger than the sum of its proper divisors (1).

8130721 is an equidigital number, since it uses as much as digits as its factorization.

8130721 is an odious number, because the sum of its binary digits is odd.

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

The square root of 8130721 is about 2851.4419159436. The cubic root of 8130721 is about 201.0834616224.

The spelling of 8130721 in words is "eight million, one hundred thirty thousand, seven hundred twenty-one".