131555509 has 2 divisors, whose sum is σ = 131555510. Its totient is φ = 131555508.

The previous prime is 131555477. The next prime is 131555549. The reversal of 131555509 is 905555131.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 102070609 + 29484900 = 10103^2 + 5430^2 .

It is a cyclic number.

It is not a de Polignac number, because 131555509 - 2⁵ = 131555477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (131555549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65777754 + 65777755.

It is an arithmetic number, because the mean of its divisors is an integer number (65777755).

Almost surely, 2^131555509 is an apocalyptic number.

It is an amenable number.

131555509 is a deficient number, since it is larger than the sum of its proper divisors (1).

131555509 is an equidigital number, since it uses as much as digits as its factorization.

131555509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16875, while the sum is 34.

The square root of 131555509 is about 11469.7649932333. The cubic root of 131555509 is about 508.5921817291.

The spelling of 131555509 in words is "one hundred thirty-one million, five hundred fifty-five thousand, five hundred nine".