645216655 has 8 divisors (see below), whose sum is σ = 774504000. Its totient is φ = 516010656.

The previous prime is 645216629. The next prime is 645216667. The reversal of 645216655 is 556612546.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 645216655 - 2²⁵ = 611662223 is a prime.

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 7 ways as a sum of consecutive naturals, for example, 1255 + ... + 35944.

It is an arithmetic number, because the mean of its divisors is an integer number (96813000).

Almost surely, 2^645216655 is an apocalyptic number.

645216655 is a deficient number, since it is larger than the sum of its proper divisors (129287345).

645216655 is a wasteful number, since it uses less digits than its factorization.

645216655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40673.

The product of its digits is 216000, while the sum is 40.

The square root of 645216655 is about 25401.1152314224. The cubic root of 645216655 is about 864.1089892909.

The spelling of 645216655 in words is "six hundred forty-five million, two hundred sixteen thousand, six hundred fifty-five".