19391909 has 2 divisors, whose sum is σ = 19391910. Its totient is φ = 19391908.

The previous prime is 19391887. The next prime is 19391927. The reversal of 19391909 is 90919391.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18062500 + 1329409 = 4250^2 + 1153^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19391909 is a prime.

It is a super-2 number, since 2×19391909² = 752092269328562, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19391969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9695954 + 9695955.

It is an arithmetic number, because the mean of its divisors is an integer number (9695955).

Almost surely, 2^19391909 is an apocalyptic number.

It is an amenable number.

19391909 is a deficient number, since it is larger than the sum of its proper divisors (1).

19391909 is an equidigital number, since it uses as much as digits as its factorization.

19391909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19683, while the sum is 41.

The square root of 19391909 is about 4403.6245298617. The cubic root of 19391909 is about 268.6623782138.

The spelling of 19391909 in words is "nineteen million, three hundred ninety-one thousand, nine hundred nine".