645588761 has 4 divisors (see below), whose sum is σ = 646102800. Its totient is φ = 645074724.

The previous prime is 645588743. The next prime is 645588763. The reversal of 645588761 is 167885546.

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 a de Polignac number, because none of the positive numbers 2^k-645588761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645588763) 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, 255131 + ... + 257648.

It is an arithmetic number, because the mean of its divisors is an integer number (161525700).

Almost surely, 2^645588761 is an apocalyptic number.

It is an amenable number.

645588761 is a deficient number, since it is larger than the sum of its proper divisors (514039).

645588761 is a wasteful number, since it uses less digits than its factorization.

645588761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 514038.

The product of its digits is 1612800, while the sum is 50.

The square root of 645588761 is about 25408.4387753360. The cubic root of 645588761 is about 864.2750721845.

The spelling of 645588761 in words is "six hundred forty-five million, five hundred eighty-eight thousand, seven hundred sixty-one".