19118913661 has 2 divisors, whose sum is σ = 19118913662. Its totient is φ = 19118913660.

The previous prime is 19118913641. The next prime is 19118913719. The reversal of 19118913661 is 16631981191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12924279225 + 6194634436 = 113685^2 + 78706^2 .

It is a cyclic number.

It is not a de Polignac number, because 19118913661 - 2¹³ = 19118905469 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19118913601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9559456830 + 9559456831.

It is an arithmetic number, because the mean of its divisors is an integer number (9559456831).

Almost surely, 2^19118913661 is an apocalyptic number.

It is an amenable number.

19118913661 is a deficient number, since it is larger than the sum of its proper divisors (1).

19118913661 is an equidigital number, since it uses as much as digits as its factorization.

19118913661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 69984, while the sum is 46.

The spelling of 19118913661 in words is "nineteen billion, one hundred eighteen million, nine hundred thirteen thousand, six hundred sixty-one".