131721156209 has 2 divisors, whose sum is σ = 131721156210. Its totient is φ = 131721156208.

The previous prime is 131721156191. The next prime is 131721156241. The reversal of 131721156209 is 902651127131.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 102668976400 + 29052179809 = 320420^2 + 170447^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-131721156209 is a prime.

It is not a weakly prime, because it can be changed into another prime (131721156299) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65860578104 + 65860578105.

It is an arithmetic number, because the mean of its divisors is an integer number (65860578105).

Almost surely, 2^131721156209 is an apocalyptic number.

It is an amenable number.

131721156209 is a deficient number, since it is larger than the sum of its proper divisors (1).

131721156209 is an equidigital number, since it uses as much as digits as its factorization.

131721156209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 22680, while the sum is 38.

The spelling of 131721156209 in words is "one hundred thirty-one billion, seven hundred twenty-one million, one hundred fifty-six thousand, two hundred nine".