155509993 has 2 divisors, whose sum is σ = 155509994. Its totient is φ = 155509992.

The previous prime is 155509979. The next prime is 155510021. The reversal of 155509993 is 399905551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 115605504 + 39904489 = 10752^2 + 6317^2 .

It is a cyclic number.

It is not a de Polignac number, because 155509993 - 2⁵ = 155509961 is a prime.

It is not a weakly prime, because it can be changed into another prime (155509493) 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, 77754996 + 77754997.

It is an arithmetic number, because the mean of its divisors is an integer number (77754997).

Almost surely, 2^155509993 is an apocalyptic number.

It is an amenable number.

155509993 is a deficient number, since it is larger than the sum of its proper divisors (1).

155509993 is an equidigital number, since it uses as much as digits as its factorization.

155509993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 273375, while the sum is 46.

The square root of 155509993 is about 12470.3645896982. The cubic root of 155509993 is about 537.7570350243.

The spelling of 155509993 in words is "one hundred fifty-five million, five hundred nine thousand, nine hundred ninety-three".