55665581 has 2 divisors, whose sum is σ = 55665582. Its totient is φ = 55665580.

The previous prime is 55665569. The next prime is 55665601. The reversal of 55665581 is 18556655.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55636681 + 28900 = 7459^2 + 170^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55665581 is a prime.

It is a super-2 number, since 2×55665581² = 6197313816135122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55665541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27832790 + 27832791.

It is an arithmetic number, because the mean of its divisors is an integer number (27832791).

Almost surely, 2^55665581 is an apocalyptic number.

It is an amenable number.

55665581 is a deficient number, since it is larger than the sum of its proper divisors (1).

55665581 is an equidigital number, since it uses as much as digits as its factorization.

55665581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 180000, while the sum is 41.

The square root of 55665581 is about 7460.9370054974. The cubic root of 55665581 is about 381.8231434643.

The spelling of 55665581 in words is "fifty-five million, six hundred sixty-five thousand, five hundred eighty-one".