131820509 has 2 divisors, whose sum is σ = 131820510. Its totient is φ = 131820508.

The previous prime is 131820503. The next prime is 131820523. The reversal of 131820509 is 905028131.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73908409 + 57912100 = 8597^2 + 7610^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-131820509 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (131820503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65910254 + 65910255.

It is an arithmetic number, because the mean of its divisors is an integer number (65910255).

Almost surely, 2^131820509 is an apocalyptic number.

It is an amenable number.

131820509 is a deficient number, since it is larger than the sum of its proper divisors (1).

131820509 is an equidigital number, since it uses as much as digits as its factorization.

131820509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 131820509 is about 11481.3112927052. The cubic root of 131820509 is about 508.9334484029.

The spelling of 131820509 in words is "one hundred thirty-one million, eight hundred twenty thousand, five hundred nine".