1918220985 has 12 divisors (see below), whose sum is σ = 3324916452. Its totient is φ = 1023051168.

The previous prime is 1918220971. The next prime is 1918221029. The reversal of 1918220985 is 5890228191.

It can be written as a sum of positive squares in 2 ways, for example, as 1140480441 + 777740544 = 33771^2 + 27888^2 .

It is not a de Polignac number, because 1918220985 - 2¹¹ = 1918218937 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 42627133 = 1918220985 / (1 + 9 + 1 + 8 + 2 + 2 + 0 + 9 + 8 + 5).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1918220985.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21313522 + ... + 21313611.

It is an arithmetic number, because the mean of its divisors is an integer number (277076371).

Almost surely, 2^1918220985 is an apocalyptic number.

1918220985 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1918220985 is a deficient number, since it is larger than the sum of its proper divisors (1406695467).

1918220985 is a wasteful number, since it uses less digits than its factorization.

1918220985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42627144 (or 42627141 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 45.

The square root of 1918220985 is about 43797.4997574062. The cubic root of 1918220985 is about 1242.5090078386.

The spelling of 1918220985 in words is "one billion, nine hundred eighteen million, two hundred twenty thousand, nine hundred eighty-five".