999997643 has 2 divisors, whose sum is σ = 999997644. Its totient is φ = 999997642.

The previous prime is 999997639. The next prime is 999997673. The reversal of 999997643 is 346799999.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 999997643 - 2² = 999997639 is a prime.

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 999997643.

It is not a weakly prime, because it can be changed into another prime (999997673) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499998821 + 499998822.

It is an arithmetic number, because the mean of its divisors is an integer number (499998822).

Almost surely, 2^999997643 is an apocalyptic number.

999997643 is a deficient number, since it is larger than the sum of its proper divisors (1).

999997643 is an equidigital number, since it uses as much as digits as its factorization.

999997643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 29760696, while the sum is 65.

The square root of 999997643 is about 31622.7393342196. The cubic root of 999997643 is about 999.9992143327. Note that the first 3 decimals are identical.

The spelling of 999997643 in words is "nine hundred ninety-nine million, nine hundred ninety-seven thousand, six hundred forty-three".