209144981 has 2 divisors, whose sum is σ = 209144982. Its totient is φ = 209144980.

The previous prime is 209144939. The next prime is 209144983. The reversal of 209144981 is 189441902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 152744881 + 56400100 = 12359^2 + 7510^2 .

It is a cyclic number.

It is not a de Polignac number, because 209144981 - 2¹⁴ = 209128597 is a prime.

It is a super-2 number, since 2×209144981² = 87483246154980722, which contains 22 as substring.

Together with 209144983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209144983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104572490 + 104572491.

It is an arithmetic number, because the mean of its divisors is an integer number (104572491).

Almost surely, 2^209144981 is an apocalyptic number.

It is an amenable number.

209144981 is a deficient number, since it is larger than the sum of its proper divisors (1).

209144981 is an equidigital number, since it uses as much as digits as its factorization.

209144981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 38.

The square root of 209144981 is about 14461.8456982503. The cubic root of 209144981 is about 593.5844049228.

The spelling of 209144981 in words is "two hundred nine million, one hundred forty-four thousand, nine hundred eighty-one".