645865001 has 4 divisors (see below), whose sum is σ = 673946112. Its totient is φ = 617783892.

The previous prime is 645864997. The next prime is 645865009. The reversal of 645865001 is 100568546.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 645865001 - 2² = 645864997 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645865009) 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 3 ways as a sum of consecutive naturals, for example, 14040521 + ... + 14040566.

It is an arithmetic number, because the mean of its divisors is an integer number (168486528).

Almost surely, 2^645865001 is an apocalyptic number.

It is an amenable number.

645865001 is a deficient number, since it is larger than the sum of its proper divisors (28081111).

645865001 is a wasteful number, since it uses less digits than its factorization.

645865001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28081110.

The product of its (nonzero) digits is 28800, while the sum is 35.

The square root of 645865001 is about 25413.8741832095. The cubic root of 645865001 is about 864.3983257250.

The spelling of 645865001 in words is "six hundred forty-five million, eight hundred sixty-five thousand, one".