1378961866 has 4 divisors (see below), whose sum is σ = 2068442802. Its totient is φ = 689480932.

The previous prime is 1378961833. The next prime is 1378961873. The reversal of 1378961866 is 6681698731.

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

It can be written as a sum of positive squares in only one way, i.e., 974750841 + 404211025 = 31221^2 + 20105^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344740465 + ... + 344740468.

Almost surely, 2^1378961866 is an apocalyptic number.

1378961866 is a deficient number, since it is larger than the sum of its proper divisors (689480936).

1378961866 is an equidigital number, since it uses as much as digits as its factorization.

1378961866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 689480935.

The product of its digits is 2612736, while the sum is 55.

The square root of 1378961866 is about 37134.3757992510. The cubic root of 1378961866 is about 1113.0570346148.

The spelling of 1378961866 in words is "one billion, three hundred seventy-eight million, nine hundred sixty-one thousand, eight hundred sixty-six".