645874791 has 16 divisors (see below), whose sum is σ = 878217984. Its totient is φ = 422141184.

The previous prime is 645874783. The next prime is 645874793. The reversal of 645874791 is 197478546.

It is not a de Polignac number, because 645874791 - 2³ = 645874783 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645874793) 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 15 ways as a sum of consecutive naturals, for example, 20766 + ... + 41508.

It is an arithmetic number, because the mean of its divisors is an integer number (54888624).

Almost surely, 2^645874791 is an apocalyptic number.

645874791 is a deficient number, since it is larger than the sum of its proper divisors (232343193).

645874791 is a wasteful number, since it uses less digits than its factorization.

645874791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20950.

The product of its digits is 1693440, while the sum is 51.

The square root of 645874791 is about 25414.0667938054. The cubic root of 645874791 is about 864.4026932099.

It can be divided in two parts, 64587 and 4791, that added together give a triangular number (69378 = T₃₇₂).

The spelling of 645874791 in words is "six hundred forty-five million, eight hundred seventy-four thousand, seven hundred ninety-one".