1978266905 has 8 divisors (see below), whose sum is σ = 2412837384. Its totient is φ = 1556668800.

The previous prime is 1978266893. The next prime is 1978266919. The reversal of 1978266905 is 5096628791.

It can be written as a sum of positive squares in 4 ways, for example, as 236790544 + 1741476361 = 15388^2 + 41731^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1978266905 - 2⁴ = 1978266889 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3242756 + ... + 3243365.

It is an arithmetic number, because the mean of its divisors is an integer number (301604673).

Almost surely, 2^1978266905 is an apocalyptic number.

It is an amenable number.

1978266905 is a deficient number, since it is larger than the sum of its proper divisors (434570479).

1978266905 is an equidigital number, since it uses as much as digits as its factorization.

1978266905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6486187.

The product of its (nonzero) digits is 1632960, while the sum is 53.

The square root of 1978266905 is about 44477.7124524182. The cubic root of 1978266905 is about 1255.3407549703.

The spelling of 1978266905 in words is "one billion, nine hundred seventy-eight million, two hundred sixty-six thousand, nine hundred five".