131209999 has 4 divisors (see below), whose sum is σ = 131733000. Its totient is φ = 130687000.

The previous prime is 131209997. The next prime is 131210021. The reversal of 131209999 is 999902131.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 131209999 - 2¹ = 131209997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131209997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 261124 + ... + 261625.

It is an arithmetic number, because the mean of its divisors is an integer number (32933250).

Almost surely, 2^131209999 is an apocalyptic number.

131209999 is a deficient number, since it is larger than the sum of its proper divisors (523001).

131209999 is an equidigital number, since it uses as much as digits as its factorization.

131209999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 523000.

The product of its (nonzero) digits is 39366, while the sum is 43.

The square root of 131209999 is about 11454.6933175882. The cubic root of 131209999 is about 508.1465453894.

The spelling of 131209999 in words is "one hundred thirty-one million, two hundred nine thousand, nine hundred ninety-nine".