19657957909 has 2 divisors, whose sum is σ = 19657957910. Its totient is φ = 19657957908.

The previous prime is 19657957861. The next prime is 19657957933. The reversal of 19657957909 is 90975975691.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13138202884 + 6519755025 = 114622^2 + 80745^2 .

It is a cyclic number.

It is not a de Polignac number, because 19657957909 - 2²³ = 19649569301 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19657957609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9828978954 + 9828978955.

It is an arithmetic number, because the mean of its divisors is an integer number (9828978955).

Almost surely, 2^19657957909 is an apocalyptic number.

It is an amenable number.

19657957909 is a deficient number, since it is larger than the sum of its proper divisors (1).

19657957909 is an equidigital number, since it uses as much as digits as its factorization.

19657957909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48223350, while the sum is 67.

The spelling of 19657957909 in words is "nineteen billion, six hundred fifty-seven million, nine hundred fifty-seven thousand, nine hundred nine".