1550511505561 has 2 divisors, whose sum is σ = 1550511505562. Its totient is φ = 1550511505560.

The previous prime is 1550511505559. The next prime is 1550511505597. The reversal of 1550511505561 is 1655051150551.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1300156379536 + 250355126025 = 1140244^2 + 500355^2 .

It is a cyclic number.

It is not a de Polignac number, because 1550511505561 - 2¹ = 1550511505559 is a prime.

Together with 1550511505559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1550511505531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 775255752780 + 775255752781.

It is an arithmetic number, because the mean of its divisors is an integer number (775255752781).

Almost surely, 2^{1550511505561} is an apocalyptic number.

It is an amenable number.

1550511505561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1550511505561 is an equidigital number, since it uses as much as digits as its factorization.

1550511505561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 93750, while the sum is 40.

The spelling of 1550511505561 in words is "one trillion, five hundred fifty billion, five hundred eleven million, five hundred five thousand, five hundred sixty-one".