6815561 has 2 divisors, whose sum is σ = 6815562. Its totient is φ = 6815560.

The previous prime is 6815533. The next prime is 6815573. The reversal of 6815561 is 1655186.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6405961 + 409600 = 2531^2 + 640^2 .

It is a cyclic number.

It is not a de Polignac number, because 6815561 - 2¹⁰ = 6814537 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (6815161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3407780 + 3407781.

It is an arithmetic number, because the mean of its divisors is an integer number (3407781).

Almost surely, 2^6815561 is an apocalyptic number.

It is an amenable number.

6815561 is a deficient number, since it is larger than the sum of its proper divisors (1).

6815561 is an equidigital number, since it uses as much as digits as its factorization.

6815561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7200, while the sum is 32.

The square root of 6815561 is about 2610.6629426259. The cubic root of 6815561 is about 189.5980514704.

The spelling of 6815561 in words is "six million, eight hundred fifteen thousand, five hundred sixty-one".