16423643666 has 4 divisors (see below), whose sum is σ = 24635465502. Its totient is φ = 8211821832.

The previous prime is 16423643651. The next prime is 16423643693. The reversal of 16423643666 is 66634632461.

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., 12852983641 + 3570660025 = 113371^2 + 59755^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 16423643666.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4105910915 + ... + 4105910918.

Almost surely, 2^16423643666 is an apocalyptic number.

16423643666 is a deficient number, since it is larger than the sum of its proper divisors (8211821836).

16423643666 is an equidigital number, since it uses as much as digits as its factorization.

16423643666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8211821835.

The product of its digits is 2239488, while the sum is 47.

The spelling of 16423643666 in words is "sixteen billion, four hundred twenty-three million, six hundred forty-three thousand, six hundred sixty-six".