55775561 has 2 divisors, whose sum is σ = 55775562. Its totient is φ = 55775560.

The previous prime is 55775549. The next prime is 55775563. The reversal of 55775561 is 16557755.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53655625 + 2119936 = 7325^2 + 1456^2 .

It is a cyclic number.

It is not a de Polignac number, because 55775561 - 2¹⁴ = 55759177 is a prime.

It is a super-2 number, since 2×55775561² = 6221826409729442, which contains 22 as substring.

Together with 55775563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (55775563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27887780 + 27887781.

It is an arithmetic number, because the mean of its divisors is an integer number (27887781).

Almost surely, 2^55775561 is an apocalyptic number.

It is an amenable number.

55775561 is a deficient number, since it is larger than the sum of its proper divisors (1).

55775561 is an equidigital number, since it uses as much as digits as its factorization.

55775561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 183750, while the sum is 41.

The square root of 55775561 is about 7468.3037565434. The cubic root of 55775561 is about 382.0744374918.

The spelling of 55775561 in words is "fifty-five million, seven hundred seventy-five thousand, five hundred sixty-one".