645944867 has 4 divisors (see below), whose sum is σ = 658132560. Its totient is φ = 633757176.

The previous prime is 645944851. The next prime is 645944891. The reversal of 645944867 is 768449546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645944867 - 2⁴ = 645944851 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (53), and also a Moran number because the ratio is a prime number: 12187639 = 645944867 / (6 + 4 + 5 + 9 + 4 + 4 + 8 + 6 + 7).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645944837) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6093767 + ... + 6093872.

It is an arithmetic number, because the mean of its divisors is an integer number (164533140).

Almost surely, 2^645944867 is an apocalyptic number.

645944867 is a deficient number, since it is larger than the sum of its proper divisors (12187693).

645944867 is a wasteful number, since it uses less digits than its factorization.

645944867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12187692.

The product of its digits is 5806080, while the sum is 53.

The square root of 645944867 is about 25415.4454416994. The cubic root of 645944867 is about 864.4339540123.

The spelling of 645944867 in words is "six hundred forty-five million, nine hundred forty-four thousand, eight hundred sixty-seven".