645808917 has 64 divisors (see below), whose sum is σ = 1035820800. Its totient is φ = 354170880.

The previous prime is 645808897. The next prime is 645808921. The reversal of 645808917 is 719808546.

645808917 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 645808917 - 2¹² = 645804821 is a prime.

It is a zygodrome in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645808967) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 880683 + ... + 881415.

It is an arithmetic number, because the mean of its divisors is an integer number (16184700).

Almost surely, 2^645808917 is an apocalyptic number.

It is an amenable number.

645808917 is a deficient number, since it is larger than the sum of its proper divisors (390011883).

645808917 is a wasteful number, since it uses less digits than its factorization.

645808917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 838.

The product of its (nonzero) digits is 483840, while the sum is 48.

The square root of 645808917 is about 25412.7707462213. The cubic root of 645808917 is about 864.3733048518.

The spelling of 645808917 in words is "six hundred forty-five million, eight hundred eight thousand, nine hundred seventeen".