155243993 has 2 divisors, whose sum is σ = 155243994. Its totient is φ = 155243992.

The previous prime is 155243981. The next prime is 155244007. The reversal of 155243993 is 399342551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 152448409 + 2795584 = 12347^2 + 1672^2 .

It is a cyclic number.

It is not a de Polignac number, because 155243993 - 2⁶ = 155243929 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 155243993.

It is not a weakly prime, because it can be changed into another prime (155243093) 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, 77621996 + 77621997.

It is an arithmetic number, because the mean of its divisors is an integer number (77621997).

Almost surely, 2^155243993 is an apocalyptic number.

It is an amenable number.

155243993 is a deficient number, since it is larger than the sum of its proper divisors (1).

155243993 is an equidigital number, since it uses as much as digits as its factorization.

155243993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145800, while the sum is 41.

The square root of 155243993 is about 12459.6947394388. The cubic root of 155243993 is about 537.4502487213.

The spelling of 155243993 in words is "one hundred fifty-five million, two hundred forty-three thousand, nine hundred ninety-three".