645978759 has 16 divisors (see below), whose sum is σ = 902195712. Its totient is φ = 410350688.

The previous prime is 645978757. The next prime is 645978761. The reversal of 645978759 is 957879546.

It is an interprime number because it is at equal distance from previous prime (645978757) and next prime (645978761).

It is a cyclic number.

It is not a de Polignac number, because 645978759 - 2¹ = 645978757 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645978757) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 349 + ... + 35945.

It is an arithmetic number, because the mean of its divisors is an integer number (56387232).

Almost surely, 2^645978759 is an apocalyptic number.

645978759 is a gapful number since it is divisible by the number (69) formed by its first and last digit.

645978759 is a deficient number, since it is larger than the sum of its proper divisors (256216953).

645978759 is a wasteful number, since it uses less digits than its factorization.

645978759 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35886.

The product of its digits is 19051200, while the sum is 60.

The square root of 645978759 is about 25416.1121928591. The cubic root of 645978759 is about 864.4490723733.

The spelling of 645978759 in words is "six hundred forty-five million, nine hundred seventy-eight thousand, seven hundred fifty-nine".