999998641 has 2 divisors, whose sum is σ = 999998642. Its totient is φ = 999998640.

The previous prime is 999998639. The next prime is 999998653. The reversal of 999998641 is 146899999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 961248016 + 38750625 = 31004^2 + 6225^2 .

It is an emirp because it is prime and its reverse (146899999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 999998641 - 2¹ = 999998639 is a prime.

Together with 999998639, it forms a pair of twin primes.

It is a nialpdrome in base 10.

It is not a weakly prime, because it can be changed into another prime (999998621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499999320 + 499999321.

It is an arithmetic number, because the mean of its divisors is an integer number (499999321).

Almost surely, 2^999998641 is an apocalyptic number.

It is an amenable number.

999998641 is a deficient number, since it is larger than the sum of its proper divisors (1).

999998641 is an equidigital number, since it uses as much as digits as its factorization.

999998641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11337408, while the sum is 64.

The square root of 999998641 is about 31622.7551139998. The cubic root of 999998641 is about 999.9995469998. Note that the first 3 decimals are identical.

The spelling of 999998641 in words is "nine hundred ninety-nine million, nine hundred ninety-eight thousand, six hundred forty-one".