19121909 has 2 divisors, whose sum is σ = 19121910. Its totient is φ = 19121908.

The previous prime is 19121899. The next prime is 19121953. The reversal of 19121909 is 90912191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18679684 + 442225 = 4322^2 + 665^2 .

It is a cyclic number.

It is not a de Polignac number, because 19121909 - 2⁸ = 19121653 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19121969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9560954 + 9560955.

It is an arithmetic number, because the mean of its divisors is an integer number (9560955).

Almost surely, 2^19121909 is an apocalyptic number.

It is an amenable number.

19121909 is a deficient number, since it is larger than the sum of its proper divisors (1).

19121909 is an equidigital number, since it uses as much as digits as its factorization.

19121909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1458, while the sum is 32.

The square root of 19121909 is about 4372.8605054358. The cubic root of 19121909 is about 267.4096541785.

The spelling of 19121909 in words is "nineteen million, one hundred twenty-one thousand, nine hundred nine".