19995643 has 2 divisors, whose sum is σ = 19995644. Its totient is φ = 19995642.

The previous prime is 19995637. The next prime is 19995667. The reversal of 19995643 is 34659991.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19995643 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 19995593 and 19995602.

It is not a weakly prime, because it can be changed into another prime (19995673) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9997821 + 9997822.

It is an arithmetic number, because the mean of its divisors is an integer number (9997822).

Almost surely, 2^19995643 is an apocalyptic number.

19995643 is a deficient number, since it is larger than the sum of its proper divisors (1).

19995643 is an equidigital number, since it uses as much as digits as its factorization.

19995643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 262440, while the sum is 46.

The square root of 19995643 is about 4471.6488010576. The cubic root of 19995643 is about 271.4220490320.

The spelling of 19995643 in words is "nineteen million, nine hundred ninety-five thousand, six hundred forty-three".