1381378666 has 16 divisors (see below), whose sum is σ = 2165486400. Its totient is φ = 659642368.

The previous prime is 1381378657. The next prime is 1381378699. The reversal of 1381378666 is 6668731831.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7530 + ... + 53098.

It is an arithmetic number, because the mean of its divisors is an integer number (135342900).

Almost surely, 2^1381378666 is an apocalyptic number.

1381378666 is a deficient number, since it is larger than the sum of its proper divisors (784107734).

1381378666 is a wasteful number, since it uses less digits than its factorization.

1381378666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46253.

The product of its digits is 870912, while the sum is 49.

The square root of 1381378666 is about 37166.9028303409. The cubic root of 1381378666 is about 1113.7069114766.

The spelling of 1381378666 in words is "one billion, three hundred eighty-one million, three hundred seventy-eight thousand, six hundred sixty-six".