19423991 has 2 divisors, whose sum is σ = 19423992. Its totient is φ = 19423990.

The previous prime is 19423951. The next prime is 19423993. The reversal of 19423991 is 19932491.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19423991 - 2¹⁰ = 19422967 is a prime.

Together with 19423993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19423993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9711995 + 9711996.

It is an arithmetic number, because the mean of its divisors is an integer number (9711996).

Almost surely, 2^19423991 is an apocalyptic number.

19423991 is a deficient number, since it is larger than the sum of its proper divisors (1).

19423991 is an equidigital number, since it uses as much as digits as its factorization.

19423991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17496, while the sum is 38.

The square root of 19423991 is about 4407.2657056275. The cubic root of 19423991 is about 268.8104550494.

The spelling of 19423991 in words is "nineteen million, four hundred twenty-three thousand, nine hundred ninety-one".