645399117 has 24 divisors (see below), whose sum is σ = 1050976640. Its totient is φ = 391149000.

The previous prime is 645399077. The next prime is 645399143. The reversal of 645399117 is 711993546.

It is not a de Polignac number, because 645399117 - 2¹⁵ = 645366349 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645399317) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 95509 + ... + 102042.

Almost surely, 2^645399117 is an apocalyptic number.

It is an amenable number.

645399117 is a deficient number, since it is larger than the sum of its proper divisors (405577523).

645399117 is a wasteful number, since it uses less digits than its factorization.

645399117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197582 (or 197565 counting only the distinct ones).

The product of its digits is 204120, while the sum is 45.

The square root of 645399117 is about 25404.7065914960. The cubic root of 645399117 is about 864.1904359354.

It can be divided in two parts, 6453 and 99117, that added together give a triangular number (105570 = T₄₅₉).

The spelling of 645399117 in words is "six hundred forty-five million, three hundred ninety-nine thousand, one hundred seventeen".