1917908945 has 4 divisors (see below), whose sum is σ = 2301490740. Its totient is φ = 1534327152.

The previous prime is 1917908917. The next prime is 1917908957. The reversal of 1917908945 is 5498097191.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1011176401 + 906732544 = 31799^2 + 30112^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1917908945 is a prime.

It is a super-2 number, since 2×1917908945² = 7356749442622026050, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 191790890 + ... + 191790899.

It is an arithmetic number, because the mean of its divisors is an integer number (575372685).

Almost surely, 2^1917908945 is an apocalyptic number.

It is an amenable number.

1917908945 is a deficient number, since it is larger than the sum of its proper divisors (383581795).

1917908945 is an equidigital number, since it uses as much as digits as its factorization.

1917908945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 383581794.

The product of its (nonzero) digits is 816480, while the sum is 53.

The square root of 1917908945 is about 43793.9373087189. The cubic root of 1917908945 is about 1242.4416305588.

The spelling of 1917908945 in words is "one billion, nine hundred seventeen million, nine hundred eight thousand, nine hundred forty-five".