155521913 has 2 divisors, whose sum is σ = 155521914. Its totient is φ = 155521912.

The previous prime is 155521903. The next prime is 155521987. The reversal of 155521913 is 319125551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 150013504 + 5508409 = 12248^2 + 2347^2 .

It is an emirp because it is prime and its reverse (319125551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 155521913 - 2¹⁴ = 155505529 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 155521913.

It is not a weakly prime, because it can be changed into another prime (155521903) 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, 77760956 + 77760957.

It is an arithmetic number, because the mean of its divisors is an integer number (77760957).

Almost surely, 2^155521913 is an apocalyptic number.

It is an amenable number.

155521913 is a deficient number, since it is larger than the sum of its proper divisors (1).

155521913 is an equidigital number, since it uses as much as digits as its factorization.

155521913 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6750, while the sum is 32.

The square root of 155521913 is about 12470.8425136396. The cubic root of 155521913 is about 537.7707745488.

The spelling of 155521913 in words is "one hundred fifty-five million, five hundred twenty-one thousand, nine hundred thirteen".