1971990668 has 6 divisors (see below), whose sum is σ = 3450983676. Its totient is φ = 985995332.

The previous prime is 1971990623. The next prime is 1971990679. The reversal of 1971990668 is 8660991791.

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, 246498830 + ... + 246498837.

It is an arithmetic number, because the mean of its divisors is an integer number (575163946).

Almost surely, 2^1971990668 is an apocalyptic number.

It is an amenable number.

1971990668 is a deficient number, since it is larger than the sum of its proper divisors (1478993008).

1971990668 is a wasteful number, since it uses less digits than its factorization.

1971990668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 492997671 (or 492997669 counting only the distinct ones).

The product of its (nonzero) digits is 1469664, while the sum is 56.

The square root of 1971990668 is about 44407.1015491892. The cubic root of 1971990668 is about 1254.0117865207.

The spelling of 1971990668 in words is "one billion, nine hundred seventy-one million, nine hundred ninety thousand, six hundred sixty-eight".