155345221 has 2 divisors, whose sum is σ = 155345222. Its totient is φ = 155345220.

The previous prime is 155345219. The next prime is 155345227. The reversal of 155345221 is 122543551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 125216100 + 30129121 = 11190^2 + 5489^2 .

It is a cyclic number.

It is not a de Polignac number, because 155345221 - 2¹ = 155345219 is a prime.

Together with 155345219, it forms a pair of twin primes.

It is a nialpdrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 155345221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155345227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77672610 + 77672611.

It is an arithmetic number, because the mean of its divisors is an integer number (77672611).

Almost surely, 2^155345221 is an apocalyptic number.

It is an amenable number.

155345221 is a deficient number, since it is larger than the sum of its proper divisors (1).

155345221 is an equidigital number, since it uses as much as digits as its factorization.

155345221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6000, while the sum is 28.

The square root of 155345221 is about 12463.7562957561. The cubic root of 155345221 is about 537.5670394839.

Adding to 155345221 its reverse (122543551), we get a palindrome (277888772).

The spelling of 155345221 in words is "one hundred fifty-five million, three hundred forty-five thousand, two hundred twenty-one".