999959561 has 2 divisors, whose sum is σ = 999959562. Its totient is φ = 999959560.

The previous prime is 999959557. The next prime is 999959563. The reversal of 999959561 is 165959999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 844483600 + 155475961 = 29060^2 + 12469^2 .

It is a cyclic number.

It is not a de Polignac number, because 999959561 - 2² = 999959557 is a prime.

It is a Sophie Germain prime.

Together with 999959563, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 999959494 and 999959503.

It is not a weakly prime, because it can be changed into another prime (999959563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499979780 + 499979781.

It is an arithmetic number, because the mean of its divisors is an integer number (499979781).

Almost surely, 2^999959561 is an apocalyptic number.

It is an amenable number.

999959561 is a deficient number, since it is larger than the sum of its proper divisors (1).

999959561 is an equidigital number, since it uses as much as digits as its factorization.

999959561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8857350, while the sum is 62.

The square root of 999959561 is about 31622.1371984880. The cubic root of 999959561 is about 999.9865201516.

The spelling of 999959561 in words is "nine hundred ninety-nine million, nine hundred fifty-nine thousand, five hundred sixty-one".