645668075 has 48 divisors (see below), whose sum is σ = 952814016. Its totient is φ = 429158400.

The previous prime is 645668063. The next prime is 645668077. The reversal of 645668075 is 570866546.

It is not a de Polignac number, because 645668075 - 2⁴ = 645668059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645668077) 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 47 ways as a sum of consecutive naturals, for example, 124535 + ... + 129615.

It is an arithmetic number, because the mean of its divisors is an integer number (19850292).

Almost surely, 2^645668075 is an apocalyptic number.

645668075 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

645668075 is a deficient number, since it is larger than the sum of its proper divisors (307145941).

645668075 is a wasteful number, since it uses less digits than its factorization.

645668075 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5144 (or 5139 counting only the distinct ones).

The product of its (nonzero) digits is 1209600, while the sum is 47.

The square root of 645668075 is about 25409.9995080677. Note that the first 3 decimals coincide. The cubic root of 645668075 is about 864.3104643258.

The spelling of 645668075 in words is "six hundred forty-five million, six hundred sixty-eight thousand, seventy-five".