645085044 has 18 divisors (see below), whose sum is σ = 1630631730. Its totient is φ = 215028336.

The previous prime is 645085039. The next prime is 645085057. The reversal of 645085044 is 440580546.

645085044 is a `hidden beast` number, since 64 + 508 + 50 + 44 = 666.

It can be written as a sum of positive squares in only one way, i.e., 569395044 + 75690000 = 23862^2 + 8700^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×645085044² = 832269427984963872, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 17919029 = 645085044 / (6 + 4 + 5 + 0 + 8 + 5 + 0 + 4 + 4).

It is a congruent number.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 8959479 + ... + 8959550.

Almost surely, 2^645085044 is an apocalyptic number.

It is an amenable number.

645085044 is an abundant number, since it is smaller than the sum of its proper divisors (985546686).

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

645085044 is a wasteful number, since it uses less digits than its factorization.

645085044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17919039 (or 17919034 counting only the distinct ones).

The product of its (nonzero) digits is 76800, while the sum is 36.

The square root of 645085044 is about 25398.5244453295. The cubic root of 645085044 is about 864.0502317760.

The spelling of 645085044 in words is "six hundred forty-five million, eighty-five thousand, forty-four".