205973981 has 2 divisors, whose sum is σ = 205973982. Its totient is φ = 205973980.

The previous prime is 205973969. The next prime is 205973983. The reversal of 205973981 is 189379502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 202606756 + 3367225 = 14234^2 + 1835^2 .

It is a cyclic number.

It is not a de Polignac number, because 205973981 - 2¹⁴ = 205957597 is a prime.

It is a super-2 number, since 2×205973981² = 84850561697976722, which contains 22 as substring.

Together with 205973983, 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 (205973983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102986990 + 102986991.

It is an arithmetic number, because the mean of its divisors is an integer number (102986991).

Almost surely, 2^205973981 is an apocalyptic number.

It is an amenable number.

205973981 is a deficient number, since it is larger than the sum of its proper divisors (1).

205973981 is an equidigital number, since it uses as much as digits as its factorization.

205973981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 136080, while the sum is 44.

The square root of 205973981 is about 14351.7936509692. The cubic root of 205973981 is about 590.5691921589.

The spelling of 205973981 in words is "two hundred five million, nine hundred seventy-three thousand, nine hundred eighty-one".