6551566561 has 2 divisors, whose sum is σ = 6551566562. Its totient is φ = 6551566560.

The previous prime is 6551566547. The next prime is 6551566601. The reversal of 6551566561 is 1656651556.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4658881536 + 1892685025 = 68256^2 + 43505^2 .

It is a cyclic number.

It is not a de Polignac number, because 6551566561 - 2²⁵ = 6518012129 is a prime.

It is not a weakly prime, because it can be changed into another prime (6551564561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3275783280 + 3275783281.

It is an arithmetic number, because the mean of its divisors is an integer number (3275783281).

Almost surely, 2^6551566561 is an apocalyptic number.

It is an amenable number.

6551566561 is a deficient number, since it is larger than the sum of its proper divisors (1).

6551566561 is an equidigital number, since it uses as much as digits as its factorization.

6551566561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 810000, while the sum is 46.

The square root of 6551566561 is about 80941.7479487563. The cubic root of 6551566561 is about 1871.1777838767.

The spelling of 6551566561 in words is "six billion, five hundred fifty-one million, five hundred sixty-six thousand, five hundred sixty-one".