1918995509 has 2 divisors, whose sum is σ = 1918995510. Its totient is φ = 1918995508.

The previous prime is 1918995461. The next prime is 1918995541. The reversal of 1918995509 is 9055998191.

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., 1910127025 + 8868484 = 43705^2 + 2978^2 .

It is an emirp because it is prime and its reverse (9055998191) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1918995509 - 2¹⁶ = 1918929973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1918995209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 959497754 + 959497755.

It is an arithmetic number, because the mean of its divisors is an integer number (959497755).

Almost surely, 2^1918995509 is an apocalyptic number.

It is an amenable number.

1918995509 is a deficient number, since it is larger than the sum of its proper divisors (1).

1918995509 is an equidigital number, since it uses as much as digits as its factorization.

1918995509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1312200, while the sum is 56.

The square root of 1918995509 is about 43806.3409679466. The cubic root of 1918995509 is about 1242.6762154682.

The spelling of 1918995509 in words is "one billion, nine hundred eighteen million, nine hundred ninety-five thousand, five hundred nine".