645739218 has 12 divisors (see below), whose sum is σ = 1399101678. Its totient is φ = 215246400.

The previous prime is 645739189. The next prime is 645739219. The reversal of 645739218 is 812937546.

645739218 is a `hidden beast` number, since 64 + 573 + 9 + 2 + 18 = 666.

It can be written as a sum of positive squares in only one way, i.e., 487658889 + 158080329 = 22083^2 + 12573^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (645739219) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17937183 + ... + 17937218.

Almost surely, 2^645739218 is an apocalyptic number.

645739218 is an abundant number, since it is smaller than the sum of its proper divisors (753362460).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645739218 is a wasteful number, since it uses less digits than its factorization.

645739218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35874409 (or 35874406 counting only the distinct ones).

The product of its digits is 362880, while the sum is 45.

The square root of 645739218 is about 25411.3993711484. The cubic root of 645739218 is about 864.3422078710.

The spelling of 645739218 in words is "six hundred forty-five million, seven hundred thirty-nine thousand, two hundred eighteen".