645668356 has 24 divisors (see below), whose sum is σ = 1156791384. Its totient is φ = 315244800.

The previous prime is 645668311. The next prime is 645668399. The reversal of 645668356 is 653866546.

It can be written as a sum of positive squares in 4 ways, for example, as 366109956 + 279558400 = 19134^2 + 16720^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18546 + ... + 40438.

It is an arithmetic number, because the mean of its divisors is an integer number (48199641).

Almost surely, 2^645668356 is an apocalyptic number.

It is an amenable number.

645668356 is a deficient number, since it is larger than the sum of its proper divisors (511123028).

645668356 is a wasteful number, since it uses less digits than its factorization.

645668356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22071 (or 22069 counting only the distinct ones).

The product of its digits is 3110400, while the sum is 49.

The square root of 645668356 is about 25410.0050373864. The cubic root of 645668356 is about 864.3105897108.

The spelling of 645668356 in words is "six hundred forty-five million, six hundred sixty-eight thousand, three hundred fifty-six".