13555981 has 2 divisors, whose sum is σ = 13555982. Its totient is φ = 13555980.

The previous prime is 13555967. The next prime is 13555999. The reversal of 13555981 is 18955531.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12187081 + 1368900 = 3491^2 + 1170^2 .

It is a cyclic number.

It is not a de Polignac number, because 13555981 - 2⁹ = 13555469 is a prime.

It is a super-2 number, since 2×13555981² = 367529241744722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 13555981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13555921) 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, 6777990 + 6777991.

It is an arithmetic number, because the mean of its divisors is an integer number (6777991).

Almost surely, 2^13555981 is an apocalyptic number.

It is an amenable number.

13555981 is a deficient number, since it is larger than the sum of its proper divisors (1).

13555981 is an equidigital number, since it uses as much as digits as its factorization.

13555981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27000, while the sum is 37.

The square root of 13555981 is about 3681.8447821710. The cubic root of 13555981 is about 238.4388309363.

The spelling of 13555981 in words is "thirteen million, five hundred fifty-five thousand, nine hundred eighty-one".