999981659 has 2 divisors, whose sum is σ = 999981660. Its totient is φ = 999981658.

The previous prime is 999981637. The next prime is 999981713. The reversal of 999981659 is 956189999.

It is a weak prime.

It is an emirp because it is prime and its reverse (956189999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 999981659 - 2⁸ = 999981403 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 999981595 and 999981604.

It is not a weakly prime, because it can be changed into another prime (999911659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499990829 + 499990830.

It is an arithmetic number, because the mean of its divisors is an integer number (499990830).

Almost surely, 2^999981659 is an apocalyptic number.

999981659 is a deficient number, since it is larger than the sum of its proper divisors (1).

999981659 is an equidigital number, since it uses as much as digits as its factorization.

999981659 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14171760, while the sum is 65.

The square root of 999981659 is about 31622.4866036812. The cubic root of 999981659 is about 999.9938862960.

The spelling of 999981659 in words is "nine hundred ninety-nine million, nine hundred eighty-one thousand, six hundred fifty-nine".