1663631866 has 16 divisors (see below), whose sum is σ = 2845488744. Its totient is φ = 722663424.

The previous prime is 1663631843. The next prime is 1663631869. The reversal of 1663631866 is 6681363661.

It can be written as a sum of positive squares in 4 ways, for example, as 1081423225 + 582208641 = 32885^2 + 24129^2 .

It is not an unprimeable number, because it can be changed into a prime (1663631869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1881495 + ... + 1882378.

Almost surely, 2^1663631866 is an apocalyptic number.

1663631866 is a deficient number, since it is larger than the sum of its proper divisors (1181856878).

1663631866 is a wasteful number, since it uses less digits than its factorization.

1663631866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3763905.

The product of its digits is 559872, while the sum is 46.

The square root of 1663631866 is about 40787.6435455641. The cubic root of 1663631866 is about 1184.9110334556.

The spelling of 1663631866 in words is "one billion, six hundred sixty-three million, six hundred thirty-one thousand, eight hundred sixty-six".