6561577501 has 2 divisors, whose sum is σ = 6561577502. Its totient is φ = 6561577500.

The previous prime is 6561577481. The next prime is 6561577537. The reversal of 6561577501 is 1057751656.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3823567225 + 2738010276 = 61835^2 + 52326^2 .

It is a cyclic number.

It is not a de Polignac number, because 6561577501 - 2²¹ = 6559480349 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6561577801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3280788750 + 3280788751.

It is an arithmetic number, because the mean of its divisors is an integer number (3280788751).

Almost surely, 2^6561577501 is an apocalyptic number.

It is an amenable number.

6561577501 is a deficient number, since it is larger than the sum of its proper divisors (1).

6561577501 is an equidigital number, since it uses as much as digits as its factorization.

6561577501 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 220500, while the sum is 43.

The square root of 6561577501 is about 81003.5647425470. The cubic root of 6561577501 is about 1872.1303659980.

The spelling of 6561577501 in words is "six billion, five hundred sixty-one million, five hundred seventy-seven thousand, five hundred one".