19808491 has 2 divisors, whose sum is σ = 19808492. Its totient is φ = 19808490.

The previous prime is 19808449. The next prime is 19808501. The reversal of 19808491 is 19480891.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19808491 - 2¹¹ = 19806443 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19800491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9904245 + 9904246.

It is an arithmetic number, because the mean of its divisors is an integer number (9904246).

Almost surely, 2^19808491 is an apocalyptic number.

19808491 is a deficient number, since it is larger than the sum of its proper divisors (1).

19808491 is an equidigital number, since it uses as much as digits as its factorization.

19808491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 40.

The square root of 19808491 is about 4450.6730951621. The cubic root of 19808491 is about 270.5725891496.

The spelling of 19808491 in words is "nineteen million, eight hundred eight thousand, four hundred ninety-one".