155321813 has 2 divisors, whose sum is σ = 155321814. Its totient is φ = 155321812.

The previous prime is 155321791. The next prime is 155321833. The reversal of 155321813 is 318123551.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 153313924 + 2007889 = 12382^2 + 1417^2 .

It is a cyclic number.

It is not a de Polignac number, because 155321813 - 2¹⁴ = 155305429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155321833) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77660906 + 77660907.

It is an arithmetic number, because the mean of its divisors is an integer number (77660907).

Almost surely, 2^155321813 is an apocalyptic number.

It is an amenable number.

155321813 is a deficient number, since it is larger than the sum of its proper divisors (1).

155321813 is an equidigital number, since it uses as much as digits as its factorization.

155321813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3600, while the sum is 29.

The square root of 155321813 is about 12462.8172176278. The cubic root of 155321813 is about 537.5400372556.

The spelling of 155321813 in words is "one hundred fifty-five million, three hundred twenty-one thousand, eight hundred thirteen".