209931131 has 2 divisors, whose sum is σ = 209931132. Its totient is φ = 209931130.

The previous prime is 209931091. The next prime is 209931149. The reversal of 209931131 is 131139902.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209931131 is a prime.

It is a super-2 number, since 2×209931131² = 88142159525878322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 209931094 and 209931103.

It is not a weakly prime, because it can be changed into another prime (209931431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104965565 + 104965566.

It is an arithmetic number, because the mean of its divisors is an integer number (104965566).

Almost surely, 2^209931131 is an apocalyptic number.

209931131 is a deficient number, since it is larger than the sum of its proper divisors (1).

209931131 is an equidigital number, since it uses as much as digits as its factorization.

209931131 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1458, while the sum is 29.

The square root of 209931131 is about 14489.0003450894. Note that the first 3 decimals coincide. The cubic root of 209931131 is about 594.3272116703.

The spelling of 209931131 in words is "two hundred nine million, nine hundred thirty-one thousand, one hundred thirty-one".