999961643 has 2 divisors, whose sum is σ = 999961644. Its totient is φ = 999961642.

The previous prime is 999961631. The next prime is 999961649. The reversal of 999961643 is 346169999.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 999961643 - 2⁶ = 999961579 is a prime.

It is not a weakly prime, because it can be changed into another prime (999961649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499980821 + 499980822.

It is an arithmetic number, because the mean of its divisors is an integer number (499980822).

Almost surely, 2^999961643 is an apocalyptic number.

999961643 is a deficient number, since it is larger than the sum of its proper divisors (1).

999961643 is an equidigital number, since it uses as much as digits as its factorization.

999961643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2834352, while the sum is 56.

The square root of 999961643 is about 31622.1701184470. The cubic root of 999961643 is about 999.9872141699.

The spelling of 999961643 in words is "nine hundred ninety-nine million, nine hundred sixty-one thousand, six hundred forty-three".