645513791 has 8 divisors (see below), whose sum is σ = 725393760. Its totient is φ = 569951712.

The previous prime is 645513751. The next prime is 645513793. The reversal of 645513791 is 197315546.

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 645513791 - 2²² = 641319487 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645513793) 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 7 ways as a sum of consecutive naturals, for example, 1079156 + ... + 1079753.

It is an arithmetic number, because the mean of its divisors is an integer number (90674220).

Almost surely, 2^645513791 is an apocalyptic number.

645513791 is a deficient number, since it is larger than the sum of its proper divisors (79879969).

645513791 is a wasteful number, since it uses less digits than its factorization.

645513791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2158945.

The product of its digits is 113400, while the sum is 41.

The square root of 645513791 is about 25406.9634352474. The cubic root of 645513791 is about 864.2416157933.

The spelling of 645513791 in words is "six hundred forty-five million, five hundred thirteen thousand, seven hundred ninety-one".