209643139 has 2 divisors, whose sum is σ = 209643140. Its totient is φ = 209643138.

The previous prime is 209643121. The next prime is 209643151. The reversal of 209643139 is 931346902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 209643139 - 2⁹ = 209642627 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 209643098 and 209643107.

It is not a weakly prime, because it can be changed into another prime (209653139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104821569 + 104821570.

It is an arithmetic number, because the mean of its divisors is an integer number (104821570).

Almost surely, 2^209643139 is an apocalyptic number.

209643139 is a deficient number, since it is larger than the sum of its proper divisors (1).

209643139 is an equidigital number, since it uses as much as digits as its factorization.

209643139 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34992, while the sum is 37.

The square root of 209643139 is about 14479.0586365274. The cubic root of 209643139 is about 594.0553132784.

The spelling of 209643139 in words is "two hundred nine million, six hundred forty-three thousand, one hundred thirty-nine".