645813549 has 12 divisors (see below), whose sum is σ = 938429856. Its totient is φ = 427963272.

The previous prime is 645813541. The next prime is 645813551. The reversal of 645813549 is 945318546.

645813549 is a `hidden beast` number, since 64 + 581 + 3 + 5 + 4 + 9 = 666.

It is not a de Polignac number, because 645813549 - 2³ = 645813541 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645813541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 213339 + ... + 216344.

It is an arithmetic number, because the mean of its divisors is an integer number (78202488).

Almost surely, 2^645813549 is an apocalyptic number.

It is an amenable number.

645813549 is a deficient number, since it is larger than the sum of its proper divisors (292616307).

645813549 is a wasteful number, since it uses less digits than its factorization.

645813549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 429856 (or 429853 counting only the distinct ones).

The product of its digits is 518400, while the sum is 45.

The square root of 645813549 is about 25412.8618813387. The cubic root of 645813549 is about 864.3753713906.

The spelling of 645813549 in words is "six hundred forty-five million, eight hundred thirteen thousand, five hundred forty-nine".