155388661 has 2 divisors, whose sum is σ = 155388662. Its totient is φ = 155388660.

The previous prime is 155388643. The next prime is 155388671. The reversal of 155388661 is 166883551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 126562500 + 28826161 = 11250^2 + 5369^2 .

It is a cyclic number.

It is not a de Polignac number, because 155388661 - 2¹⁷ = 155257589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155388671) 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, 77694330 + 77694331.

It is an arithmetic number, because the mean of its divisors is an integer number (77694331).

Almost surely, 2^155388661 is an apocalyptic number.

It is an amenable number.

155388661 is a deficient number, since it is larger than the sum of its proper divisors (1).

155388661 is an equidigital number, since it uses as much as digits as its factorization.

155388661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 172800, while the sum is 43.

The square root of 155388661 is about 12465.4988267618. The cubic root of 155388661 is about 537.6171423788.

The spelling of 155388661 in words is "one hundred fifty-five million, three hundred eighty-eight thousand, six hundred sixty-one".