19909823 has 2 divisors, whose sum is σ = 19909824. Its totient is φ = 19909822.

The previous prime is 19909793. The next prime is 19909837. The reversal of 19909823 is 32890991.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19909823 - 2⁶ = 19909759 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19509823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9954911 + 9954912.

It is an arithmetic number, because the mean of its divisors is an integer number (9954912).

Almost surely, 2^19909823 is an apocalyptic number.

19909823 is a deficient number, since it is larger than the sum of its proper divisors (1).

19909823 is an equidigital number, since it uses as much as digits as its factorization.

19909823 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 34992, while the sum is 41.

The square root of 19909823 is about 4462.0424695424. The cubic root of 19909823 is about 271.0331835747.

The spelling of 19909823 in words is "nineteen million, nine hundred nine thousand, eight hundred twenty-three".