645921166 has 16 divisors (see below), whose sum is σ = 1057425840. Its totient is φ = 293471680.

The previous prime is 645921163. The next prime is 645921179. The reversal of 645921166 is 661129546.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645921163) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 60090 + ... + 70018.

It is an arithmetic number, because the mean of its divisors is an integer number (66089115).

Almost surely, 2^645921166 is an apocalyptic number.

645921166 is a deficient number, since it is larger than the sum of its proper divisors (411504674).

645921166 is a wasteful number, since it uses less digits than its factorization.

645921166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12899.

The product of its digits is 77760, while the sum is 40.

The square root of 645921166 is about 25414.9791658384. The cubic root of 645921166 is about 864.4233812834.

The spelling of 645921166 in words is "six hundred forty-five million, nine hundred twenty-one thousand, one hundred sixty-six".