19909157 has 2 divisors, whose sum is σ = 19909158. Its totient is φ = 19909156.

The previous prime is 19909139. The next prime is 19909163. The reversal of 19909157 is 75190991.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11792356 + 8116801 = 3434^2 + 2849^2 .

It is a cyclic number.

It is not a de Polignac number, because 19909157 - 2²⁰ = 18860581 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19909187) 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, 9954578 + 9954579.

It is an arithmetic number, because the mean of its divisors is an integer number (9954579).

Almost surely, 2^19909157 is an apocalyptic number.

It is an amenable number.

19909157 is a deficient number, since it is larger than the sum of its proper divisors (1).

19909157 is an equidigital number, since it uses as much as digits as its factorization.

19909157 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25515, while the sum is 41.

The square root of 19909157 is about 4461.9678394179. The cubic root of 19909157 is about 271.0301614465.

The spelling of 19909157 in words is "nineteen million, nine hundred nine thousand, one hundred fifty-seven".