645110666 has 4 divisors (see below), whose sum is σ = 967666002. Its totient is φ = 322555332.

The previous prime is 645110617. The next prime is 645110707. The reversal of 645110666 is 666011546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 666011546 = 2 ⋅333005773.

It can be written as a sum of positive squares in only one way, i.e., 526932025 + 118178641 = 22955^2 + 10871^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161277665 + ... + 161277668.

Almost surely, 2^645110666 is an apocalyptic number.

645110666 is a deficient number, since it is larger than the sum of its proper divisors (322555336).

645110666 is a wasteful number, since it uses less digits than its factorization.

645110666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322555335.

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 645110666 is about 25399.0288397017. The cubic root of 645110666 is about 864.0616713023.

The spelling of 645110666 in words is "six hundred forty-five million, one hundred ten thousand, six hundred sixty-six".