645311666 has 8 divisors (see below), whose sum is σ = 968451120. Its totient is φ = 322494628.

The previous prime is 645311663. The next prime is 645311671. The reversal of 645311666 is 666113546.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (645311663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75536 + ... + 83643.

It is an arithmetic number, because the mean of its divisors is an integer number (121056390).

Almost surely, 2^645311666 is an apocalyptic number.

645311666 is a deficient number, since it is larger than the sum of its proper divisors (323139454).

645311666 is a wasteful number, since it uses less digits than its factorization.

645311666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161208.

The product of its digits is 77760, while the sum is 38.

The square root of 645311666 is about 25402.9853757388. The cubic root of 645311666 is about 864.1514018300.

The spelling of 645311666 in words is "six hundred forty-five million, three hundred eleven thousand, six hundred sixty-six".