8131209 has 4 divisors (see below), whose sum is σ = 10841616. Its totient is φ = 5420804.

The previous prime is 8131177. The next prime is 8131229. The reversal of 8131209 is 9021318.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 8131209 - 2⁵ = 8131177 is a prime.

It is a super-2 number, since 2×8131209² = 132233119603362, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (8131229) 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, 1355199 + ... + 1355204.

It is an arithmetic number, because the mean of its divisors is an integer number (2710404).

Almost surely, 2^8131209 is an apocalyptic number.

It is an amenable number.

8131209 is a deficient number, since it is larger than the sum of its proper divisors (2710407).

8131209 is a wasteful number, since it uses less digits than its factorization.

8131209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2710406.

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 8131209 is about 2851.5274854015. The cubic root of 8131209 is about 201.0874845032.

The spelling of 8131209 in words is "eight million, one hundred thirty-one thousand, two hundred nine".