155131209 has 24 divisors (see below), whose sum is σ = 227050304. Its totient is φ = 102060000.

The previous prime is 155131199. The next prime is 155131213. The reversal of 155131209 is 902131551.

It is not a de Polignac number, because 155131209 - 2⁵ = 155131177 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155131279) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 286479 + ... + 287019.

Almost surely, 2^155131209 is an apocalyptic number.

It is an amenable number.

155131209 is a deficient number, since it is larger than the sum of its proper divisors (71919095).

155131209 is a wasteful number, since it uses less digits than its factorization.

155131209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 909 (or 906 counting only the distinct ones).

The product of its (nonzero) digits is 1350, while the sum is 27.

The square root of 155131209 is about 12455.1679635403. The cubic root of 155131209 is about 537.3200655332.

The spelling of 155131209 in words is "one hundred fifty-five million, one hundred thirty-one thousand, two hundred nine".