1918978909 has 4 divisors (see below), whose sum is σ = 1919950560. Its totient is φ = 1918007260.

The previous prime is 1918978877. The next prime is 1918978927. The reversal of 1918978909 is 9098798191.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1918978909 - 2⁵ = 1918978877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1918978949) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 482857 + ... + 486814.

It is an arithmetic number, because the mean of its divisors is an integer number (479987640).

Almost surely, 2^1918978909 is an apocalyptic number.

It is an amenable number.

1918978909 is a deficient number, since it is larger than the sum of its proper divisors (971651).

1918978909 is an equidigital number, since it uses as much as digits as its factorization.

1918978909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 971650.

The product of its (nonzero) digits is 2939328, while the sum is 61.

The square root of 1918978909 is about 43806.1514972498. The cubic root of 1918978909 is about 1242.6726322595.

The spelling of 1918978909 in words is "one billion, nine hundred eighteen million, nine hundred seventy-eight thousand, nine hundred nine".