209490731 has 2 divisors, whose sum is σ = 209490732. Its totient is φ = 209490730.

The previous prime is 209490727. The next prime is 209490733. The reversal of 209490731 is 137094902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 209490731 - 2² = 209490727 is a prime.

It is a super-2 number, since 2×209490731² = 87772732749828722, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 209490733, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 209490691 and 209490700.

It is not a weakly prime, because it can be changed into another prime (209490733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104745365 + 104745366.

It is an arithmetic number, because the mean of its divisors is an integer number (104745366).

Almost surely, 2^209490731 is an apocalyptic number.

209490731 is a deficient number, since it is larger than the sum of its proper divisors (1).

209490731 is an equidigital number, since it uses as much as digits as its factorization.

209490731 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13608, while the sum is 35.

The square root of 209490731 is about 14473.7946302965. The cubic root of 209490731 is about 593.9113213951.

The spelling of 209490731 in words is "two hundred nine million, four hundred ninety thousand, seven hundred thirty-one".