13555561 has 2 divisors, whose sum is σ = 13555562. Its totient is φ = 13555560.

The previous prime is 13555547. The next prime is 13555583. The reversal of 13555561 is 16555531.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13366336 + 189225 = 3656^2 + 435^2 .

It is a cyclic number.

It is not a de Polignac number, because 13555561 - 2⁷ = 13555433 is a prime.

It is not a weakly prime, because it can be changed into another prime (13555541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6777780 + 6777781.

It is an arithmetic number, because the mean of its divisors is an integer number (6777781).

Almost surely, 2^13555561 is an apocalyptic number.

It is an amenable number.

13555561 is a deficient number, since it is larger than the sum of its proper divisors (1).

13555561 is an equidigital number, since it uses as much as digits as its factorization.

13555561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11250, while the sum is 31.

The square root of 13555561 is about 3681.7877451043. The cubic root of 13555561 is about 238.4363684232.

It can be divided in two parts, 135 and 55561, that added together give a square (55696 = 236²).

The spelling of 13555561 in words is "thirteen million, five hundred fifty-five thousand, five hundred sixty-one".