209920939 has 2 divisors, whose sum is σ = 209920940. Its totient is φ = 209920938.

The previous prime is 209920903. The next prime is 209920961. The reversal of 209920939 is 939029902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 209920939 - 2¹⁹ = 209396651 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 209920895 and 209920904.

It is not a weakly prime, because it can be changed into another prime (209920339) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104960469 + 104960470.

It is an arithmetic number, because the mean of its divisors is an integer number (104960470).

Almost surely, 2^209920939 is an apocalyptic number.

209920939 is a deficient number, since it is larger than the sum of its proper divisors (1).

209920939 is an equidigital number, since it uses as much as digits as its factorization.

209920939 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 78732, while the sum is 43.

The square root of 209920939 is about 14488.6486257346. The cubic root of 209920939 is about 594.3175934669.

The spelling of 209920939 in words is "two hundred nine million, nine hundred twenty thousand, nine hundred thirty-nine".