155320217 has 4 divisors (see below), whose sum is σ = 167267940. Its totient is φ = 143372496.

The previous prime is 155320159. The next prime is 155320247. The reversal of 155320217 is 712023551.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 64899136 + 90421081 = 8056^2 + 9509^2 .

It is a cyclic number.

It is not a de Polignac number, because 155320217 - 2⁶ = 155320153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155320247) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5973842 + ... + 5973867.

It is an arithmetic number, because the mean of its divisors is an integer number (41816985).

Almost surely, 2^155320217 is an apocalyptic number.

It is an amenable number.

155320217 is a deficient number, since it is larger than the sum of its proper divisors (11947723).

155320217 is a wasteful number, since it uses less digits than its factorization.

155320217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11947722.

The product of its (nonzero) digits is 2100, while the sum is 26.

The square root of 155320217 is about 12462.7531869968. The cubic root of 155320217 is about 537.5381960958.

Adding to 155320217 its reverse (712023551), we get a palindrome (867343768).

The spelling of 155320217 in words is "one hundred fifty-five million, three hundred twenty thousand, two hundred seventeen".