998906861 has 2 divisors, whose sum is σ = 998906862. Its totient is φ = 998906860.

The previous prime is 998906851. The next prime is 998906863. The reversal of 998906861 is 168609899.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 946792900 + 52113961 = 30770^2 + 7219^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-998906861 is a prime.

It is a Sophie Germain prime.

Together with 998906863, 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 = 998906797 and 998906806.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (998906863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499453430 + 499453431.

It is an arithmetic number, because the mean of its divisors is an integer number (499453431).

Almost surely, 2^998906861 is an apocalyptic number.

It is an amenable number.

998906861 is a deficient number, since it is larger than the sum of its proper divisors (1).

998906861 is an equidigital number, since it uses as much as digits as its factorization.

998906861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1679616, while the sum is 56.

The square root of 998906861 is about 31605.4878304386. The cubic root of 998906861 is about 999.6354874801.

The spelling of 998906861 in words is "nine hundred ninety-eight million, nine hundred six thousand, eight hundred sixty-one".