16645331666 has 16 divisors (see below), whose sum is σ = 26182791000. Its totient is φ = 7925597568.

The previous prime is 16645331639. The next prime is 16645331693. The reversal of 16645331666 is 66613354661.

It is an interprime number because it is at equal distance from previous prime (16645331639) and next prime (16645331693).

It can be written as a sum of positive squares in 4 ways, for example, as 16639710025 + 5621641 = 128995^2 + 2371^2 .

It is a super-2 number, since 2×16645331666² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 16645331666.

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, 1961441 + ... + 1969908.

Almost surely, 2^16645331666 is an apocalyptic number.

16645331666 is a deficient number, since it is larger than the sum of its proper divisors (9537459334).

16645331666 is a wasteful number, since it uses less digits than its factorization.

16645331666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3931453.

The product of its digits is 1399680, while the sum is 47.

The spelling of 16645331666 in words is "sixteen billion, six hundred forty-five million, three hundred thirty-one thousand, six hundred sixty-six".