645166 has 4 divisors (see below), whose sum is σ = 967752. Its totient is φ = 322582.

The previous prime is 645149. The next prime is 645179. The reversal of 645166 is 661546.

645166 is nontrivially palindromic in base 5.

645166 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161290 + ... + 161293.

It is an arithmetic number, because the mean of its divisors is an integer number (241938).

2⁶⁴⁵¹⁶⁶ is an apocalyptic number.

645166 is a deficient number, since it is larger than the sum of its proper divisors (322586).

645166 is a wasteful number, since it uses less digits than its factorization.

645166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322585.

The product of its digits is 4320, while the sum is 28.

The square root of 645166 is about 803.2222606477. Note that the first 4 decimals coincide. The cubic root of 645166 is about 86.4086375395.

The spelling of 645166 in words is "six hundred forty-five thousand, one hundred sixty-six".