645908042 has 16 divisors (see below), whose sum is σ = 1044443400. Its totient is φ = 297810432.

The previous prime is 645908041. The next prime is 645908051. The reversal of 645908042 is 240809546.

It can be written as a sum of positive squares in 4 ways, for example, as 591900241 + 54007801 = 24329^2 + 7349^2 .

It is a junction number, because it is equal to n+sod(n) for n = 645907987 and 645908005.

It is not an unprimeable number, because it can be changed into a prime (645908041) 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 7 ways as a sum of consecutive naturals, for example, 14834 + ... + 38882.

Almost surely, 2^645908042 is an apocalyptic number.

645908042 is a deficient number, since it is larger than the sum of its proper divisors (398535358).

645908042 is a wasteful number, since it uses less digits than its factorization.

645908042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25097.

The product of its (nonzero) digits is 69120, while the sum is 38.

The square root of 645908042 is about 25414.7209703353. The cubic root of 645908042 is about 864.4175267149.

The spelling of 645908042 in words is "six hundred forty-five million, nine hundred eight thousand, forty-two".