71556220661 has 2 divisors, whose sum is σ = 71556220662. Its totient is φ = 71556220660.

The previous prime is 71556220643. The next prime is 71556220727. The reversal of 71556220661 is 16602265517.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61429622500 + 10126598161 = 247850^2 + 100631^2 .

It is a cyclic number.

It is not a de Polignac number, because 71556220661 - 2¹⁸ = 71555958517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71556220061) 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, 35778110330 + 35778110331.

It is an arithmetic number, because the mean of its divisors is an integer number (35778110331).

Almost surely, 2^71556220661 is an apocalyptic number.

It is an amenable number.

71556220661 is a deficient number, since it is larger than the sum of its proper divisors (1).

71556220661 is an equidigital number, since it uses as much as digits as its factorization.

71556220661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 151200, while the sum is 41.

The spelling of 71556220661 in words is "seventy-one billion, five hundred fifty-six million, two hundred twenty thousand, six hundred sixty-one".