155555591 has 2 divisors, whose sum is σ = 155555592. Its totient is φ = 155555590.

The previous prime is 155555581. The next prime is 155555597. The reversal of 155555591 is 195555551.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155555591 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155555597) 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, 77777795 + 77777796.

It is an arithmetic number, because the mean of its divisors is an integer number (77777796).

Almost surely, 2^155555591 is an apocalyptic number.

155555591 is a deficient number, since it is larger than the sum of its proper divisors (1).

155555591 is an equidigital number, since it uses as much as digits as its factorization.

155555591 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 140625, while the sum is 41.

The square root of 155555591 is about 12472.1927101853. The cubic root of 155555591 is about 537.8095895228.

The spelling of 155555591 in words is "one hundred fifty-five million, five hundred fifty-five thousand, five hundred ninety-one".