131717821 has 2 divisors, whose sum is σ = 131717822. Its totient is φ = 131717820.

The previous prime is 131717813. The next prime is 131717843. The reversal of 131717821 is 128717131.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 108388921 + 23328900 = 10411^2 + 4830^2 .

It is a cyclic number.

It is not a de Polignac number, because 131717821 - 2³ = 131717813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (131717801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65858910 + 65858911.

It is an arithmetic number, because the mean of its divisors is an integer number (65858911).

Almost surely, 2^131717821 is an apocalyptic number.

It is an amenable number.

131717821 is a deficient number, since it is larger than the sum of its proper divisors (1).

131717821 is an equidigital number, since it uses as much as digits as its factorization.

131717821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2352, while the sum is 31.

The square root of 131717821 is about 11476.8384583909. The cubic root of 131717821 is about 508.8012612475.

The spelling of 131717821 in words is "one hundred thirty-one million, seven hundred seventeen thousand, eight hundred twenty-one".